"Objective-C iPhoneアプリ開発 入門ノート" ページ 230-231 さんぷる?

Chapter6-1_drag_affine.m

#import "ViewController.h"
 
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *image;
- (IBAction)panning:(UIPanGestureRecognizer *)sender;
@end
 
@implementation ViewController
- (IBAction)panning:(UIPanGestureRecognizer *)sender {
  if (sender.state == UIGestureRecognizerStateBegan){
    _image.center = [sender locationInView:self.view];
  }
  CGPoint trans = [sender translationInView:self.view];
  _image.transform = CGAffineTransformMakeTranslation(trans.x, trans.y);
}
@end