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  • NSUndoManager grouping problem?

    - by anonymous
    I'm working on a barebones drawing app. I'm attempting to implement undo/redo capability, so I tell the view's undoManager to save the current image before updating the display. This works perfectly (yes, I understand that redrawing/saving the entire view is not incredibly efficient, but to solve this problem before attempting to optimize the code). However, as expected, when I 'undo' or 'redo', only the minute change is reflected. My goal is to have the whole finger stroke undone/redone. To do that, I told the undoManager to [beginUndoGrouping] in the [touchesBegan] method, and to [endUndoGrouping] in [touchesEnded]. That works for a bit, but after drawing a few strokes, the app crashes, and gdb exits with exc_bad_access. I'm very grateful for any insight you can give me. - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { mouseDragged = YES; currentPoint = [[touches anyObject] locationInView:self]; UIGraphicsBeginImageContext(drawingImageView.bounds.size); [drawingImageView.image drawInRect:drawingImageView.bounds]; CGContextRef ctx = UIGraphicsGetCurrentContext(); CGContextSetLineCap(ctx, kCGLineCapRound); CGContextSetLineWidth(ctx, drawingWidth); [drawingColor setStroke]; CGContextBeginPath(ctx); CGContextMoveToPoint(ctx, previousPoint.x, previousPoint.y); CGContextAddLineToPoint(ctx, currentPoint.x, currentPoint.y); CGContextStrokePath(ctx); [self.undoManager registerUndoWithTarget:drawingImageView selector:@selector(setImage:) object:drawingImageView.image]; drawingImageView.image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); previousPoint = currentPoint; }

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  • UIRotationGestureRecognizer minimum rotation value

    - by dc
    Is it possible to set a minimum rotation value necessary for a UIRotationGestureRecognizer to transition into UIGestureRecognizerStateRecognized? I'm using multiple recognizers, and my UIRotationGestureRecognizer keeps getting called with a very small rotation (Between 1 and 15 degrees either direction) rather than my UIPinchGestureRecognizer. What I'd like to do is only have the rotation be called if the rotation is within a certain range, otherwise cancel it and let the pinch be called.

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  • Objective C selector memory managment (does this leak memory)?

    - by James Jones
    - (IBAction) someButtonCall { if(!someCondition) { someButtonCallBack = @selector(someButtonCall); [self presentModalViewController:someController animated:YES]; } else ... } //Called from someController - (void) someControllerFinished:(BOOL) ok { [self dismissModalViewControllerAnimated:YES]; if(ok) [self performSelector:someButtonCallBack]; else ... } I'm wondering if the user keeps getting into the !someCondition clause if the selector is leaked by assigning a new selector each time (the code above is hypothetical and not what i'm doing). Any help is appreciated. Thanks, James Jones

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  • How to determine if scrolling a UITableView was done by tapping the index?

    - by John Michael Zorko
    Hello, all ... I want to determine when the index (transparent alphabet) along the side of a UITableView is tapped. To be more specific, I have a sectioned UITableView that has an index, and said index does the right thing, but when the UITableView's -scrollViewDidScroll method is called, I want to be able to determine if said scrolling was the result of the user tapping the index, vs. dragging or swiping the table view itself. If anyone has ideas on how to do this, i'd love to hear about them :-) Regards, John

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  • Problem in cropping the UIImage using CGContext?

    - by Rajendra Bhole
    Hi, I developing the simple UIApplication in which i want to crop the UIImage (in .jpg format) with help of CGContext. The developed code till now as follows, CGImageRef graphicOriginalImage = [originalImage.image CGImage]; UIGraphicsBeginImageContext(originalImage.image.size); CGContextRef ctx = UIGraphicsGetCurrentContext(); CGBitmapContextCreateImage(graphicOriginalImage); CGFloat fltW = originalImage.image.size.width; CGFloat fltH = originalImage.image.size.height; CGFloat X = round(fltW/4); CGFloat Y =round(fltH/4); CGFloat width = round(X + (fltW/2)); CGFloat height = round(Y + (fltH/2)); CGContextTranslateCTM(ctx, 0, image.size.height); CGContextScaleCTM(ctx, 1.0, -1.0); CGRect rect = CGRectMake(X,Y ,width ,height); CGContextDrawImage(ctx, rect, graphicOriginalImage); croppedImage = UIGraphicsGetImageFromCurrentImageContext(); return croppedImage; } The above code is worked fine but it can't crop image. The original image memory and cropped image memory i will got same(equal to original image memory). The above code is right for cropping the image?????????????????? How i cropping the image (in behind pixels should also be crop) from the center of the image???????????? I already wasting a lot of time for developing the above code , but i didn't get answer or way to find out how to crop the image.Thanks for sending me answer in advanced.

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  • NSCalendar: Problem getting weeks in a month...

    - by AngrySpade
    I am creating a calendar control of sorts... One thing I need to know is how many weeks are there in a Month... So NSCalendar rangeOfUnit:inUnit:forDate Seems to be exactly what I need... Except I am noticing something that seems off and I can't quite figure out why this is happening... The following code... NSCalendar *calendar = [NSCalendar currentCalendar]; NSDateComponents *dateComponents = [[NSDateComponents alloc] init]; [dateComponents setYear: 2010]; [dateComponents setDay: 1]; for (int x=1; x<=12; x++) { [dateComponents setMonth: x]; NSDate *date = [calendar dateFromComponents:dateComponents]; NSLog(@"Date: %@", date); NSRange range = [calendar rangeOfUnit: NSWeekCalendarUnit inUnit: NSMonthCalendarUnit forDate:date]; NSLog(@"%d Weeks in Month %d", range.length, [dateComponents month]); } Is returning the following debug messages... 2010-03-14 13:08:10.350 Scrap[4256:207] Date: 2010-01-01 00:00:00 -0500 2010-03-14 13:08:10.351 Scrap[4256:207] 5 Weeks in Month 1 2010-03-14 13:08:10.352 Scrap[4256:207] Date: 2010-02-01 00:00:00 -0500 2010-03-14 13:08:10.352 Scrap[4256:207] 4 Weeks in Month 2 2010-03-14 13:08:10.353 Scrap[4256:207] Date: 2010-03-01 00:00:00 -0500 2010-03-14 13:08:10.353 Scrap[4256:207] 5 Weeks in Month 3 2010-03-14 13:08:10.354 Scrap[4256:207] Date: 2010-04-01 00:00:00 -0400 2010-03-14 13:08:10.355 Scrap[4256:207] 5 Weeks in Month 4 2010-03-14 13:08:10.356 Scrap[4256:207] Date: 2010-05-01 00:00:00 -0400 2010-03-14 13:08:10.357 Scrap[4256:207] 5 Weeks in Month 5 2010-03-14 13:08:10.358 Scrap[4256:207] Date: 2010-06-01 00:00:00 -0400 2010-03-14 13:08:10.358 Scrap[4256:207] 5 Weeks in Month 6 2010-03-14 13:08:10.359 Scrap[4256:207] Date: 2010-07-01 00:00:00 -0400 2010-03-14 13:08:10.360 Scrap[4256:207] 5 Weeks in Month 7 2010-03-14 13:08:10.361 Scrap[4256:207] Date: 2010-08-01 00:00:00 -0400 2010-03-14 13:08:10.364 Scrap[4256:207] 5 Weeks in Month 8 2010-03-14 13:08:10.364 Scrap[4256:207] Date: 2010-09-01 00:00:00 -0400 2010-03-14 13:08:10.365 Scrap[4256:207] 5 Weeks in Month 9 2010-03-14 13:08:10.366 Scrap[4256:207] Date: 2010-10-01 00:00:00 -0400 2010-03-14 13:08:10.366 Scrap[4256:207] 5 Weeks in Month 10 2010-03-14 13:08:10.367 Scrap[4256:207] Date: 2010-11-01 00:00:00 -0400 2010-03-14 13:08:10.367 Scrap[4256:207] 5 Weeks in Month 11 2010-03-14 13:08:10.369 Scrap[4256:207] Date: 2010-12-01 00:00:00 -0500 2010-03-14 13:08:10.369 Scrap[4256:207] 52 Weeks in Month 12 I cant quite figure out why I get 52 weeks in month 12. Any clues?

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  • Texture2D problem

    - by Anders Karlsson
    I have a problem that is driving me crazy, I want to write a number of texts on the screen using Texture2D however I only seem to be able to write the first one. If I individually write one of the labels it works but not if I write all of them, only the first label is displayed. Let me show some code: -(void)drawText:(NSString*)theString AtX:(float)X Y:(float)Y withFont:(UIFont*)aFont { // set color glColor4f(1, 0, 0, 1.0); // Enable modes needed for drawing glEnableClientState(GL_TEXTURE_COORD_ARRAY); Texture2D* textTexture = [[Texture2D alloc] initWithString:theString dimensions:viewSize // 320x480 alignment:UITextAlignmentLeft font:aFont]; glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); [textTexture drawInRect:CGRectMake(X,Y,1,1)]; glDisableClientState(GL_TEXTURE_COORD_ARRAY); [textTexture release]; } When I call this drawText once it seems to display the text properly, but if I call it a second time nothing seems to be displayed. Somebody has an idea what it could be? The states like GL_BLEND and GL_TEXTURE_2D have been enabled in the view setup function. In the Texture2D the dimensions are 512x512 as I pass the whole screen to function. If I don't pass that the text gets enlarged and fuzzy. I am a bit uncertain about that parameter. TIA for any help.

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  • Setting UIImage dimensions on UITableViewCell image

    - by bbrown
    I've got a standard UITableViewCell where I'm using the text and image properties to display a favicon.ico and a label. For the most part, this works really well since UIImage supports the ICO format. However, some sites (like Amazon.com say) have favicon.icos that make use of the ICO format's ability to store multiple sizes in the same file. Amazon stores four different sizes, all the way up to 48x48. This results in most images being 16x16 except for a few that come in at 32x32 or 48x48 and make everything look terrible. I have searched here, the official forum, the documentation, and elsewhere without success. I have tried everything that I could think of to constrain the image size. The only thing that worked was an undocumented method, which I'm not about to use. This is my first app and my first experience with Cocoa (came from C#). In case I wasn't clear in what I'm looking for, ideally the advice would center around setting the dimensions of the UIImage so that the 48x48 version would scale down to 16x16 or a method to tell UIImage to use the 16x16 version present in the ICO file. I don't necessarily need code: just a suggestion of an approach would do me fine. Does anyone have any suggestions? (I asked in the official forum as well because I've sunk more than a day into this already. If a solution is posted there, I'll put it here as well.)

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  • UITableView: Header below a section gets duplicated if a row is deleted from the section above

    - by Megasaur
    In the editing mode of one of my tableviews, I delete a row from a section. The section below has a header. The deletion of the row in the section above leads to duplication of the section header below. So I have 2 header titles, one above the other. I also tried forcing a reload of the section after the delete to no avail: [self.tableView beginUpdates]; [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:YES]; NSIndexSet * indexSet = [[NSIndexSet alloc] initWithIndexesInRange:NSMakeRange(3,1)]; [self.tableView reloadSections:indexSet withRowAnimation:UITableViewRowAnimationFade]; [indexSet release]; [self.tableView endUpdates]; Any ideas of what I have done wrong? It is also interesting that the header that failed to get removed is not "seen". If I scroll right off the content of the table view, and let it snap back, only the top header view is seen. It always ignores the header that should have been removed.

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  • Callback for camera shutter open event

    - by Raj
    Hi all, I have been working around in UIImagePickerController and am struck with a problem where I need to get the precise moment when the camera shutter opens in UIImagePickerController when the source type is set to camera (UIImagePickerControllerSourceTypeCamera). I have done some googling around and have realized that no one had such strange requirement! I looked around the docs of UIImagePickerController and UIImagePickerControllerDelegate hoping to get some delegate method / callback indicating the camera shutter open event, but did not find any. Any suggestions? Thanks for any help, Raj Pawan

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  • When should you NOT use the asterisk (*) when declaring a variable in Objective C

    - by Jason
    I have just started learning objective c and the asterisk is giving me some trouble. As I look through sample code, sometime it is used when declaring a variable and sometimes it is not. What are the "rules" for when it should be used. I thought it had something to do with the data type of the variable. (asterisk needed for object data types, not needed for simple data types like int) However, I have seen object data types such as CGPoint declared without the asterisk as well? Is there a definitive answer or does it have to do with how and what you use the variable for?

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  • UIImagePickerController does not deliver geo tag data

    - by Gregory Mace
    When I use UIImagePickerController to select a photo, either from the Camera Roll or the Photo Library, the image that gets returned to me in the method 'didFinishPickingImage' does not contain the exif data for latitude and longitude. I know that the headers are there, because they show up when imported into iPhoto, also if I upload images from the Camera Roll, they also contain the exif headers for location. Is there a way to get UIImagePickerController to deliver that information as well?

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  • ASIHTTPRequest code design

    - by nico
    I'm using ASIHTTPRequest to communicate with the server asynchronously. It works great, but I'm doing requests in different controllers and now duplicated methods are in all those controllers. What is the best way to abstract that code (requests) in a single class, so I can easily re-use the code, so I can keep the controllers more simple. I can put it in a singleton (or in the app delegate), but I don't think that's a good approach. Or maybe make my own protocol for it with delegate callback. Any advice on a good design approach would be helpful. Thanks.

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  • Lazy load pages in UIScrollView

    - by jean
    I have a UIScrollView that contains large images and am using paging to scroll between images. In order to save memory, I am loading only one image before and after the currently visible one and loading/releasing new images after a scroll has completed. The problem occurs when one scrolls quickly and scrollViewDidEndDecelerating is not called. How can I detect continuous scrolling? I could check item location on every scrollViewDidScroll but this seems a bit heavy...

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  • UIDatePicker hours are disabled

    - by user112175
    I have a UIDatePicker object and I am setting it up as follows but for some reason my hours field is disabled on the current date but minutes are not. Not exactly sure what I am missing, any help would be appreciated. UIDatePicker *picker = [[UIDatePicker alloc] init]; picker.date = [NSDate dateWithTimeIntervalSinceNow:DATE_MIN_SECONDS_OFFSET]; picker.minimumDate = [NSDate dateWithTimeIntervalSinceNow:DATE_MIN_SECONDS_OFFSET]; This is what My datepicker looks like http://img.skitch.com/20100417-d75gq78pjwjb9d37ku9msmcduc.png

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  • How do I properly handle rotation of a UIScrollView containing UIImageViews?

    - by bpapa
    I'm developing an image viewer, much like the Photos App. It's a UIScrollView with paging enabled with images loaded from the internet, so I've adapted portions of the LazyTableImages sample. The Scroll View and each ImageView inside of it have all of their autoresize mask flags set. When I first observed how resizes were happening during rotation, it looked good, but once I started trying to interact with the scroll view, I realized that I also had to programmatically change the size of the contentView. I did that by implementing didRotateFromInterfaceOrientation: in my view controller. [self.scrollView setContentSize:CGSizeMake(numberOfImages * portraitWidth, [scrollView bounds].size.height)]; With interaction behaving properly, I then discovered that, if I was viewing the second photo and rotated, portions of both the 1st and 2nd photos would be shown on the screen. I needed to change the contentOffset as well. I've tried to fix this two ways - both by using the scrollRectToVisible:animated: method of UIScrollView, as well as trying to set the contentOffset property directly. And I've experimented by putting this code in implementations of both the "one-step" and "two-step" responses to changes in Orientation. For example: -(void)didAnimateFirstHalfOfRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation { [self.scrollView setContentOffset:CGPointMake(currentlyViewedPhotoIndex * largeImageHeight,0) animated:YES]; In all cases though, it just looks janky as hell. Either I clearly see the scroll happen, or it just jumps. Uuuuuuuuuuugly! Is there a way to do this so that it behaves exactly like the Photos app does?

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  • Building a clip area in a UIView from path objects in its subviews

    - by hkatz
    I'm trying to produce a clipping area in a UIView that's generated from path objects in its subviews. For example, I might have one subview containing a square and another containing a circle. I want to be able to produce a clip in the parent superview that's the union of both these shapes. Can someone explain how to do this? About all I've been able to figure out so far is that: 1 - the superview's drawRect: method is called before its subviews' drawRects are, and 2 - the ContextRef that's accessible in all three instances is the same. Other than that I'm stumped. Thanks, Howard

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  • Any example on how to implement the new VerificationController and the KNOWN_TRANSACTIONS_KEY constant?

    - by Carles Estevadeordal
    I've been looking at implementing the new VerificationController to verify in-App-Purchases: http://developer.apple.com/library/ios/#releasenotes/StoreKit/IAP_ReceiptValidation/_index.html And I wonder if there is some example anywhere en how to validate a transaction, since it seems that the - (BOOL)verifyPurchase:(SKPaymentTransaction *)transaction; is not enough and it has to be implemented internally to verify the purchase when the data form the server is received. Another question is if anyone has a clue on what the KNOWN_TRANSACTIONS_KEY is and how to fill it, is it just the product id of the purchase?

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  • I just don't get AudioFileReadPackets

    - by Eric Christensen
    I've tried to write the smallest chunk of code to narrow down a problem. It's now just a few lines and it doesn't work, which makes it pretty clear that I have a fundamental misunderstanding of how to use AudioFileReadPackets. I've read the docs and other examples online, and apparently I'm just not getting. Could you explain it to me? Here's what this block should do: I've previously opened a file. I want to read just one packet - the first one of the file - and then print it. But it crashes on the AudioFileReadPackets line: AudioFileID mAudioFile2; AudioFileOpenURL (audioFileURL, 0x01, 0, &mAudioFile2); UInt32 *audioData2 = (UInt32 *)malloc(sizeof(UInt32) * 1); AudioFileReadPackets(mAudioFile2, false, NULL, NULL, 0, (UInt32*)1, audioData2); NSLog(@"first packet:%i",audioData2[0]); (For clarity, I've stripped out all error handling.) It's the AFRP line that crashes out. (I understand that the third and fourth argument are useful, and in my "real" code, I use them, but they're not required, right? So NULL in this case should work, right?) So then what's going on? Any guidance would be much appreciated. Thanks.

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  • Memory Leaks - Objective-C

    - by reising1
    Can anyone help point out memory leaks? I'm getting a bunch within this method and I'm not sure exactly how to fix it. - (NSMutableArray *)getTop5AndOtherKeysAndValuesFromDictionary:(NSMutableDictionary *)dict { NSLog(@"get top 5"); int sumOfAllValues = 0; NSMutableArray *arr = [[[NSMutableArray alloc] init] retain]; for(NSString *key in dict){ NSString *value = [[dict objectForKey:key] retain]; [arr addObject:value]; sumOfAllValues += [value intValue]; } //sort values NSArray *sorted = [[arr sortedArrayUsingFunction:sort context:NULL] retain]; [arr release]; //top 5 values int sumOfTop5 = 0; NSMutableArray *top5 = [[[NSMutableArray alloc] init] retain]; for(int i = 0; i < 5; i++) { int proposedIndex = [sorted count] - 1 - i; if(proposedIndex >= 0) { [top5 addObject:[sorted objectAtIndex:([sorted count] - i - 1)]]; sumOfTop5 += [[sorted objectAtIndex:([sorted count] - i - 1)] intValue]; } } [sorted release]; //copy of all keys NSMutableArray *copyOfKeys = [[[NSMutableArray alloc] init] retain]; for(NSString *key in dict) { [copyOfKeys addObject:key]; } //copy of top 5 values NSMutableArray *copyOfTop5 = [[[NSMutableArray alloc] init] retain]; for(int i = 0; i < [top5 count]; i++) { [copyOfTop5 addObject:[top5 objectAtIndex:i]]; } //get keys with top 5 values NSMutableArray *outputKeys = [[[NSMutableArray alloc] init] retain]; for(int i = 0; i < [top5 count]; i++) { NSString *targetValue = [top5 objectAtIndex:i]; for(int j = 0; j < [copyOfKeys count]; j++) { NSString *key = [copyOfKeys objectAtIndex:j]; NSString *val = [dict objectForKey:key]; if([val isEqualToString:targetValue]) { [outputKeys addObject:key]; [copyOfKeys removeObjectAtIndex:j]; break; } } } [outputKeys addObject:@"Other"]; [top5 addObject:[[NSString stringWithFormat:@"%d",(sumOfAllValues - sumOfTop5)] retain]]; NSMutableArray *output = [[NSMutableArray alloc] init]; [output addObject:outputKeys]; [output addObject:top5]; NSMutableArray *percents = [[NSMutableArray alloc] init]; int sum = sumOfAllValues; float leftOverSum = sum * 1.0f; int count = [top5 count]; float val1, val2, val3, val4, val5; if(count >= 1) val1 = ([[top5 objectAtIndex:0] intValue] * 1.0f)/sum; else val1 = 0.0f; if(count >=2) val2 = ([[top5 objectAtIndex:1] intValue] * 1.0f)/sum; else val2 = 0.0f; if(count >= 3) val3 = ([[top5 objectAtIndex:2] intValue] * 1.0f)/sum; else val3 = 0.0f; if(count >= 4) val4 = ([[top5 objectAtIndex:3] intValue] * 1.0f)/sum; else val4 = 0.0f; if(count >=5) val5 = ([[top5 objectAtIndex:4] intValue] * 1.0f)/sum; else val5 = 0.0f; if(val1 >= .00001f) { NSMutableArray *a1 = [[NSMutableArray alloc] init]; [a1 addObject:[outputKeys objectAtIndex:0]]; [a1 addObject:[top5 objectAtIndex:0]]; [a1 addObject:[NSString stringWithFormat:@"%.01f",(val1*100)]]; [percents addObject:a1]; leftOverSum -= ([[top5 objectAtIndex:0] intValue] * 1.0f); } if(val2 >= .00001f) { NSMutableArray *a2 = [[NSMutableArray alloc] init]; [a2 addObject:[outputKeys objectAtIndex:1]]; [a2 addObject:[top5 objectAtIndex:1]]; [a2 addObject:[NSString stringWithFormat:@"%.01f",(val2*100)]]; [percents addObject:a2]; leftOverSum -= ([[top5 objectAtIndex:1] intValue] * 1.0f); } if(val3 >= .00001f) { NSMutableArray *a3 = [[NSMutableArray alloc] init]; [a3 addObject:[outputKeys objectAtIndex:2]]; [a3 addObject:[top5 objectAtIndex:2]]; [a3 addObject:[NSString stringWithFormat:@"%.01f",(val3*100)]]; [percents addObject:a3]; leftOverSum -= ([[top5 objectAtIndex:2] intValue] * 1.0f); } if(val4 >= .00001f) { NSMutableArray *a4 = [[NSMutableArray alloc] init]; [a4 addObject:[outputKeys objectAtIndex:3]]; [a4 addObject:[top5 objectAtIndex:3]]; [a4 addObject:[NSString stringWithFormat:@"%.01f",(val4*100)]]; [percents addObject:a4]; leftOverSum -= ([[top5 objectAtIndex:3] intValue] * 1.0f); } if(val5 >= .00001f) { NSMutableArray *a5 = [[NSMutableArray alloc] init]; [a5 addObject:[outputKeys objectAtIndex:4]]; [a5 addObject:[top5 objectAtIndex:4]]; [a5 addObject:[NSString stringWithFormat:@"%.01f",(val5*100)]]; [percents addObject:a5]; leftOverSum -= ([[top5 objectAtIndex:4] intValue] * 1.0f); } float valOther = (leftOverSum/sum); if(valOther >= .00001f) { NSMutableArray *a6 = [[NSMutableArray alloc] init]; [a6 addObject:[outputKeys objectAtIndex:5]]; [a6 addObject:[top5 objectAtIndex:5]]; [a6 addObject:[NSString stringWithFormat:@"%.01f",(valOther*100)]]; [percents addObject:a6]; } [output addObject:percents]; NSLog(@"mu - a"); //[arr release]; NSLog(@"mu - b"); //[copyOfKeys release]; NSLog(@"mu - c"); //[copyOfTop5 release]; NSLog(@"mu - c"); //[outputKeys release]; //[top5 release]; //[percents release]; return output; }

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  • NSOperation and UIKit problem

    - by Infinity
    Hello guys! I am doing my download with an object which was inherited from NSOperation. I have read the documentation and when my operation finished I must call the [self.delegate performSelectorOnMainThread:@selector(operationDidFinish:) withObject:self waitUntilDone:YES]; method. It needs to be called on the main thread, because the UIKit is not thread safe and the documentation says this in these non thread safe frameworks cases. In the delegate method I am drawing a pdf or an image, but because it is drawn on the main thread the User Interface is very laggy until the drawing is finished. Maybe can you suggest me a good way to avoid this problem?

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