UIImageView移动和拖拽手势

项目中要求对UIImageView进行放大和拖动，所以记录一下。

@interface PutQuestionToViewController ()\

@property (nonatomic, strong) UIImageView *maxImageView;

/** 记录大图的原始尺寸 */
@property (nonatomic, assign) CGRect oldFrame;

/** 大图的最大放大尺寸 */
@property (nonatomic, assign) CGRect largeFrame;

@end

@implementation PutQuestionToViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    // 添加图片
        self.maxImageView.image = [UIImage imageNamed:@"picture"];
    
}

//MARK: 大图maxImageView
- (UIImageView *)maxImageView {
    if (!_maxImageView) {
        _maxImageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 64, SCREENSIZE.width, SCREENSIZE.height - 64)];
        _oldFrame = _maxImageView.frame;// 记录原始尺寸
        _largeFrame = CGRectMake(0 - SCREENSIZE.width, 0 - SCREENSIZE.height, 3 * _oldFrame.size.width, 3 * _oldFrame.size.height);// 制定最大放大尺寸////
        
        // 允许imageView响应用户操作(切记要让ImageView响应用户操作)
        _maxImageView.userInteractionEnabled = YES;
        
        // 添加点击手势
        UITapGestureRecognizer *tap  = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(maxImageViewTap)];
        tap.numberOfTapsRequired = 1;// 点击次数
        tap.numberOfTouchesRequired = 1;// 几个手指
        [_maxImageView addGestureRecognizer:tap];
        
        // 添加缩放手势
        UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchView:)];
        [_maxImageView addGestureRecognizer:pinchGestureRecognizer];
        
        // 添加移动手势
        UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panView:)];
        [_maxImageView addGestureRecognizer:panGestureRecognizer];
        
    }
    [self.view addSubview:_maxImageView];
    return _maxImageView;
}

#pragma mark- maxImageView手势事件处理
//MARK: 点击手势
- (void)maxImageViewTap {
    // 让图片回复最初大小，并从父视图移除
    self.maxImageView.frame = self.oldFrame;
    [self.maxImageView removeFromSuperview];
}

//MARK: 缩放手势
- (void) pinchView:(UIPinchGestureRecognizer *)pinchGestureRecognizer {
    UIView *view = pinchGestureRecognizer.view;
    if (pinchGestureRecognizer.state == UIGestureRecognizerStateBegan || pinchGestureRecognizer.state == UIGestureRecognizerStateChanged) {
        view.transform = CGAffineTransformScale(view.transform, pinchGestureRecognizer.scale, pinchGestureRecognizer.scale);
        if (self.maxImageView.frame.size.width < self.oldFrame.size.width) { //让图片无法缩得比原图小

            self.maxImageView.frame = self.oldFrame;
        }
        if (self.maxImageView.frame.size.width > 3 * self.oldFrame.size.width) {// 设置最大放大图
            self.maxImageView.frame = self.largeFrame;
        }
        pinchGestureRecognizer.scale = 1;
    }
}
//MARK: 拖拉手势
- (void) panView:(UIPanGestureRecognizer *)panGestureRecognizer {
    UIView *view = panGestureRecognizer.view;
    if (panGestureRecognizer.state == UIGestureRecognizerStateBegan || panGestureRecognizer.state == UIGestureRecognizerStateChanged) {
        CGPoint translation = [panGestureRecognizer translationInView:view.superview];
        double X ;
        double Y;
       // 在此需要判断中心点有没有越界（即图片移动后保证不和屏幕边界产生空白处）
        if (view.center.x + translation.x < - (CGRectGetWidth(view.frame)/2 - SCREENSIZE.width)) {
            X = - (CGRectGetWidth(self.maxImageView.frame)/2 - SCREENSIZE.width);
        }else if(view.center.x + translation.x > CGRectGetWidth(view.frame)/2) {
            X = CGRectGetWidth(view.frame)/2;
        }else {
            X = view.center.x + translation.x;
        }
        if (view.center.y + translation.y < - (CGRectGetHeight(view.frame)/2 - SCREENSIZE.height)) {
            Y = - (CGRectGetHeight(view.frame)/2 - SCREENSIZE.height);
        }else if(view.center.y + translation.y - 64 > CGRectGetHeight(view.frame)/2) {
            Y = CGRectGetHeight(view.frame)/2 + 64;
        }else {
            Y = view.center.y + translation.y;
        }
        
        [view setCenter:(CGPoint){X, Y}];
    }
    [panGestureRecognizer setTranslation:CGPointZero inView:view.superview];
    
}


@end

参考：
【IOS】使用手势对UIImageView进行缩放、旋转和移动