iOS 限制图片的缩放比例 设置捏合手势的缩放比例

捏合手势目测可以无限放大图片,但是一般情况下,我们只允许用户在一定的比例范围内进行缩放

方案:用一个全局的值记录总的缩放比例,当超出范围后就不允许继续超范围,只能回到缩放范围

如果嫌麻烦这里打包好的分类,三行代码搞定:https://github.com/iOSSinger/SGZoomImage

具体代码如下:

#import "ViewController.h"

#define MaxSCale 2.0  //最大缩放比例
#define MinScale 0.5  //最小缩放比例

#import "UIImageView+Zoom.h"
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@property (nonatomic,assign) CGFloat totalScale;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.totalScale = 1.0;
    
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinch:)];
    [self.imageView addGestureRecognizer:pinch];
    
}

- (void)pinch:(UIPinchGestureRecognizer *)recognizer{

    CGFloat scale = recognizer.scale;
    
    //放大情况
    if(scale > 1.0){
        if(self.totalScale > MaxSCale) return;
    }
    
    //缩小情况
    if (scale < 1.0) {
        if (self.totalScale < MinScale) return;
    }

    self.imageView.transform = CGAffineTransformScale(self.imageView.transform, scale, scale);
    self.totalScale *=scale;
    recognizer.scale = 1.0;
   
}

@end