About updating a View using in iPhone using Objective C.
- by Tattat
I have a scene, called testScene, it works like this:
@interface testScene : myScene {
IBOutlet UIView *subview;
IBOutlet UIView *drawingCanvasView;
IBOutlet UIButton *update;
}
- (void)updateDrawingCanvas: (id) sender;
and when the user click the button, update, it will run the updateDrawingCanvas method.
So, I have a drawingCanvasView, which gave a drawingCanvas.h, and .m, it like this:
#import <UIKit/UIKit.h>
@interface DrawingCanvasView : UIView {
CGImageRef image;
}
-(void)setNeedsDisplayInRect:(CGContextRef)context;
@end
In the DrawingCanvasView, I have a drawRect method like this:
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
CGContextMoveToPoint(context, 0.0f, 0.0f);
CGContextAddLineToPoint(context, 100.0f, 100.0f);
CGContextStrokePath(context);
And I want the user click the button, and execute this, so I added a new method called setNeedsDisplayInRect:
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGContextSetStrokeColorWithColor(context, [UIColor yellowColor].CGColor);
CGContextMoveToPoint(context, 0.0f, 0.0f);
CGContextAddLineToPoint(context, 200.0f, 200.0f);
CGContextStrokePath(context);
But I can't called that in my updateDrawingCanvas method, it work like this:
- (void)updateDrawingCanvas: (id) sender{
NSLog(@"loaded");
[DrawingCanvasView setNeedsDisplayInRect:UIGraphicsGetCurrentContext()];
}
It my logic / concept right? or something I did wrong, thx.
