开发中遇到个类似脑图的一个东西，里面需要支持缩放，下面介绍一下我是怎么处理的

需要的类

UIPinchGestureRecognizer 这个就是缩放的手势

过程

1.将视图添加缩放手势

UIView *customView = [[UIView alloc] initWithFrame:[UIScreen mainScreen].bounds];

UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchView:)]; 

[customView addGestureRecognizer:pinchGestureRecognizer];

相应方法

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

@property (nonatomic,assign) CGFloat totalScale; //<? 用于记录视图即时的缩放比例

// 处理缩放手势
- (void)pinchView:(UIPinchGestureRecognizer *)pinchGestureRecognizer
{
    UIView *view = pinchGestureRecognizer.view;

    CGFloat scale = pinchGestureRecognizer.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;
    }
    
    if (pinchGestureRecognizer.state == UIGestureRecognizerStateBegan || pinchGestureRecognizer.state == UIGestureRecognizerStateChanged) {
        view.transform = CGAffineTransformScale(view.transform, pinchGestureRecognizer.scale, pinchGestureRecognizer.scale);
        pinchGestureRecognizer.scale = 1;
        self.totalScale *=scale;

    }
}

总结

最开始，并没有想好怎么限制，后来参考别人的办法，就是在处理手势的时候 适当的时候return。
值得注意的是self.totalScale一定要初始化为 1；