利用iOS手势与scrollView代理实现图片的放大缩小

@interface ViewController ()

@property (strong, nonatomic) IBOutlet UIView *redView;
@property (assign, nonatomic) CGFloat scale;//记录上次手势结束的放大倍数
@property (assign, nonatomic) CGFloat realScale;//当前手势应该放大的倍数

@end

@implementation ViewController

- (void)viewDidLoad {
 [super viewDidLoad];
 // Do any additional setup after loading the view, typically from a nib.
 UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(pinchEvent:)];

 [self.view addGestureRecognizer:pinchGesture];

 self.scale = 1;
}
- (void)pinchEvent:(UIPinchGestureRecognizer *)pinch {

 self.realScale = self.scale + （pinch.scale - 1）;//当前的放大倍数是上次的放大倍数加上当前手势pinch程度

 if (self.realScale > 10) {//设置最大放大倍数
 self.realScale = 10;
 }else if (self.realScale < 0.5){//最小放大倍数
 self.realScale = 0.5;
 }

 self.redView.transform = CGAffineTransformMakeScale(self.realScale, self.realScale);

 if (pinch.state == UIGestureRecognizerStateEnded){//当结束捏合手势时记录当前图片放大倍数

 self.scale = self.realScale;

 }

 NSLog(@"%f-------%f",self.scale,self.realScale);
}

@end

 self.scrollView.minimumZoomScale = 0.5;
 self.scrollView.maximumZoomScale = 10;

 self.scrollView.delegate = self;

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {

 return self.enlargeImage;
}

- (void)scrollViewDidZoom:(UIScrollView *)scrollView {

 CGRect frame = self.enlargeImage.frame;

 frame.origin.y = (self.scrollView.frame.size.height - self.enlargeImage.frame.size.height) > 0 ? (self.scrollView.frame.size.height - self.enlargeImage.frame.size.height) * 0.5 : 0;
 frame.origin.x = (self.scrollView.frame.size.width - self.enlargeImage.frame.size.width) > 0 ? (self.scrollView.frame.size.width - self.enlargeImage.frame.size.width) * 0.5 : 0;
 self.enlargeImage.frame = frame;

 self.scrollView.contentSize = CGSizeMake(self.enlargeImage.frame.size.width + 30, self.enlargeImage.frame.size.height + 30);
}