how to let the touchesMoved only control one view? - objective-c

Question

i create an UIButton on the view,and i want to let the touchesMoved only control the UIButton,not the whole view
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *touch = [touches anyObject];
CGPoint touchMoved = [touch locationInView:self.view];
}
i want to do like this
if i touch the UIButton,and then the UIButton can be moved with my finger,if i touch other view and my finger is moving on the screen,the UIButton does nothing.
that means the function touchesMoved only has the role of the UIButton,so how can i do it? thanks

Answer 1

I presume the code you show takes place in your custom view controller subclass, and the UIButton is a subview of its view.
Define a simple BOOL in your class that you set to NO first. Then update it in the event handling methods.
// .h
BOOL buttonTouched;
// .m
// in the viewDidLoad
buttonTouched = NO;
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
// test wether the button is touched
UITouch *touch = [touches anyObject];
CGPoint touchBegan = [touch locationInView:self.view];
if(CGRectContainsPoint(theButton.frame, touchBegan) {
buttonTouched = YES;
}
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
if(buttonTouched) {
// do it here
UITouch *touch = [touches anyObject];
CGPoint touchMoved = [touch locationInView:self.view];
CGRect newFrame = CGRectMake(touchMoved.x,
touchMoved.y,
theButton.frame.width,
theButton.frame.height);
theButton.frame = newFrame;
}
}
// when the event ends, put the BOOL back to NO
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
buttonTouched = NO;
}