iOS开发——手势识别器（用手势实现图片旋转和缩小放大）

我就是我 2022-08-21 08:56 253阅读 0赞

iOS开发中，除了有关触摸的这组方法来控制用户的手指触控外，还可以用UIGestureRecognize的衍生类来进行判断，方便了开发。  
UIGestureRecognize的子类类别有以下几种：

*  UITapGestureRecognizer //轻拍识别器
 *  UIPinchGestureRecognizer //捏合识别器
 *  UIRotationGestureRecognizer //旋转识别器
 *  UISwipeGestureRecognizer //扫动识别器
 *  UIPanGestureRecognizer //拖动识别器
 *  UILongPressGestureRecognizer //长按识别器

下面的例子我是用UIPinchGestureRecognizer和UIRotationGestureRecognizer通过手势实现图片旋转和缩小放大。

ViewController.m中的代码如下；

#import "ViewController.h"
    
    @interface ViewController ()
    
    @property(nonatomic,strong) UIImageView *imageView;
    @property(nonatomic) CGFloat lastRotation;
    
    -(void)changeImageSize:(UIPinchGestureRecognizer *)recognizer;
    -(void)rotateImage:(UIRotationGestureRecognizer *)rotateRecognizer;
    
    @end
    
    @implementation ViewController
    
    - (void)viewDidLoad {
        [super viewDidLoad];
    
        self.view.backgroundColor = [UIColor whiteColor];
    
        //在view上添加一个ImageView
        UIImageView *image = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Totoro"]];
        image.frame = CGRectMake(0, 0, 128, 128);
        self.imageView = image;
        self.imageView.center = CGPointMake(self.view.frame.size.width/2, self.view.frame.size.height/2);
        [self.view addSubview:self.imageView];
    
        //添加捏合手势识别器，changeImageSize:方法实现图片的放大与缩小
        UIPinchGestureRecognizer *pinchRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(changeImageSize:)];
        [self.view addGestureRecognizer:pinchRecognizer];
    
        //添加旋转手势识别器，rotateImage:方法实现图片的旋转
        UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc]initWithTarget:self action:@selector(rotateImage:)];
        [self.view addGestureRecognizer:rotateRecognizer];
    
    }
    
    -(void)changeImageSize:(UIPinchGestureRecognizer *)recognizer
    {
        CGRect frame = self.imageView.frame;
    
        //监听两手指滑动的距离，改变imageView的frame
        frame.size.width = recognizer.scale*128;
        frame.size.height = recognizer.scale*128;
        self.imageView.frame = frame;
    
        //保证imageView中心不动
        self.imageView.center =CGPointMake(self.view.frame.size.width/2, self.view.frame.size.height/2);
    }
    
    -(void)rotateImage:(UIRotationGestureRecognizer *)rotateRecognizer
    {
        //改变imageView的角度，使图片旋转
        if ([rotateRecognizer state]==UIGestureRecognizerStateEnded) {
            self.lastRotation = 0.0;
            return;
        }
        CGAffineTransform currentTransform = self.imageView.transform;
        CGFloat rotation = 0.0 - (self.lastRotation - rotateRecognizer.rotation);
        CGAffineTransform newTransform = CGAffineTransformRotate(currentTransform,rotation);
        self.imageView.transform = newTransform;
        self.lastRotation = rotateRecognizer.rotation;
    }
    
    
    @end

运行代码，实现效果如下：

![这里写图片描述][20160425214359922]![这里写图片描述][20160425214413425]

[20160425214359922]: https://img-blog.csdn.net/20160425214359922
[20160425214413425]: /images/20220724/8703dcc07f63431a8f687ec5675977bc.png