detect rotate gesture and scale gesture iphone sdk - iphone

Question

I want to rotate the uiimageview also scale the image view so how do i detect touch gesture that user is scaling or user is rotating?

Answer 1

Beginning in iOS 3.2, Apple introduced the use of UIGestureRecognizer's. The two that you would be interested in are UIPinchGestureRecognizer and UIRotationGestureRecognizer. To use a pinch gesture you could do the following:
- (void)viewDidLoad {
UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:#selector(handlePinchGesture:)];
[imageView addGestureRecognizer:pinch];
[pinch release];
}
- (void)handlePinchGesture:(UIGestureRecognizer *)sender {
NSLog(#"New Scale: %f", sender.scale);
}
You could do something similar for the UIRotationGestureRecognizer then.

Answer 2

in your viewcontroller.h file write down this properties
IBOutlet UIImageView *imgRotate;
CGFloat lastScale;
CGFloat lastRotation;
now in your viewcontroller.m file write the below code,
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
UIPinchGestureRecognizer *pinchRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:#selector(scale:)];
[pinchRecognizer setDelegate:self];
[imgRotate addGestureRecognizer:pinchRecognizer];
UIRotationGestureRecognizer *rotationRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:#selector(rotate:)];
[rotationRecognizer setDelegate:self];
[imgRotate addGestureRecognizer:rotationRecognizer];
}
-(void)scale:(id)sender
{
if([(UIPinchGestureRecognizer*)sender state] == UIGestureRecognizerStateEnded)
{
lastScale = 1.0;
return;
}
CGFloat scale = 1.0 - (lastScale - [(UIPinchGestureRecognizer*)sender scale]);
CGAffineTransform currentTransform = [(UIPinchGestureRecognizer*)sender view].transform;
CGAffineTransform newTransform = CGAffineTransformScale(currentTransform, scale, scale);
[[(UIPinchGestureRecognizer*)sender view] setTransform:newTransform];
[imgRotate setTransform:newTransform];
lastScale = [(UIPinchGestureRecognizer*)sender scale];
}
-(void)rotate:(id)sender
{
if([(UIRotationGestureRecognizer*)sender state] == UIGestureRecognizerStateEnded)
{
lastRotation = 0.0;
return;
}
CGFloat rotation = 0.0 - (lastRotation - [(UIRotationGestureRecognizer*)sender rotation]);
CGAffineTransform currentTransform = [(UIPinchGestureRecognizer*)sender view].transform;
CGAffineTransform newTransform = CGAffineTransformRotate(currentTransform,rotation);
[[(UIRotationGestureRecognizer*)sender view] setTransform:newTransform];
[imgRotate setTransform:newTransform];
lastRotation = [(UIRotationGestureRecognizer*)sender rotation];
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
if ([touch view] == imgRotate) {
CGPoint location = [touch locationInView:self.view];
imgRotate.center = location;
}
}