Save the position of a UIImageView - ios

Question

I have several UIImageViews that the user can drag, scale and rotate. I want the position, size and angle to persist when the user navigates to another view and comes back. How do i achieve this?
I have used the following code to pan, rotate and scale
- (void)panPiece:(UIPanGestureRecognizer *)gestureRecognizer
{
UIView *piece = [gestureRecognizer view];
[self adjustAnchorPointForGestureRecognizer:gestureRecognizer];
if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {
CGPoint translation = [gestureRecognizer translationInView:[piece superview]];
[piece setCenter:CGPointMake([piece center].x + translation.x, [piece center].y + translation.y)];
[gestureRecognizer setTranslation:CGPointZero inView:[piece superview]];
}
}
- (void)rotatePiece:(UIRotationGestureRecognizer *)gestureRecognizer
{
[self adjustAnchorPointForGestureRecognizer:gestureRecognizer];
if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {
[gestureRecognizer view].transform = CGAffineTransformRotate([[gestureRecognizer view] transform], [gestureRecognizer rotation]);
[gestureRecognizer setRotation:0];
}
}
- (void)scalePiece:(UIPinchGestureRecognizer *)gestureRecognizer
{
[self adjustAnchorPointForGestureRecognizer:gestureRecognizer];
if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {
[gestureRecognizer view].transform = CGAffineTransformScale([[gestureRecognizer view] transform], [gestureRecognizer scale], [gestureRecognizer scale]);
[gestureRecognizer setScale:1];
}
}

Answer 1

Depending on your needs you can create method, that you'll add as another target method to all your gesture recognizers.
E.g.
[panGestureRecognizer addTarget: self action: #selector(onGestureRecognizerEnd:)];
[rotationGestureRecognizer addTarget: self action: #selector(onGestureRecognizerEnd:)];
[pinchGestureRecognizer addTarget: self action: #selector(onGestureRecognizerEnd:)];
Sample implementation of that method could be:
- (void)onGestureRecognizerEnd: (UIGestureRecognizer *)gestureRecognizer
{
switch ( gestureRecognizer.state )
{
case UIGestureRecognizerStateEnded:
case UIGestureRecognizerStateCancelled:
case UIGestureRecognizerStateFailed:
{
[self _saveViewPosition: gestureRecognizer.view];
break;
}
default:
{
break;
}
}
}
_saveViewPosition: method you can implement like this:
- (void)_saveViewPosition: (UIView *)view
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setObject: [NSKeyedArchiver archivedDataWithRootObject: [NSValue valueWithCGPoint: view.center]]
forKey: [self _centerKeyForView: view]];
[defaults setObject: [NSKeyedArchiver archivedDataWithRootObject: [NSValue valueWithCGAffineTransform: view.transform]]
forKey: [self _transformKeyForView: view]];
}
For more information check Xcode project.
BR