固定范围内拖动缩放一个图片 借鉴了github中的ImageZoom

@interface ViewController ()<UIScrollViewDelegate>

@property (weak, nonatomic) IBOutlet UIScrollView *scrollView;
@property (weak, nonatomic) IBOutlet UIImageView *imageView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.scrollView.delegate = self;
    self.scrollView.minimumZoomScale = 1;
    self.scrollView.maximumZoomScale = 3;
    self.scrollView.bounces = NO;
    self.scrollView.showsHorizontalScrollIndicator = NO;
    self.scrollView.showsVerticalScrollIndicator = NO;
    
    
    
    
    NSArray * arr = @[@"亚洲",@"欧洲",@"非洲",@"北美洲",@"南美洲",@"大洋洲",@"南极洲"];
    for (NSInteger i = 0; i<7; i++) {
        UIButton *button = [[UIButton alloc]init];
        [self.imageView addSubview:button];
        
        button.titleLabel.font=[UIFont fontWithName:@"Bodoni 72 Smallcaps" size:15];
        [button setTitle:arr[i] forState:UIControlStateNormal];
        
        [button setBackgroundImage:[UIImage imageNamed:@"bg_lastminute_view"] forState:UIControlStateNormal];
        [button setBackgroundImage:[UIImage imageNamed:@"x_myOrder_green"] forState:UIControlStateSelected];
        [button setTitleColor:[UIColor colorWithWhite:0.400 alpha:1.000] forState:UIControlStateNormal];
        
        [button setTitleColor:[UIColor whiteColor] forState:UIControlStateSelected];
        
        button.tag=i+100;
        if (i==0) {
            
            button.frame = CGRectMake(W - 95, 50, 40, 25);
            
        }
        if (i == 1) {
            button.frame = CGRectMake(150, 40, 40, 25);
        }
        if (i == 2) {
            button.frame = CGRectMake(190, 100,40, 25);
        }
        
        if (i == 3) {
            button.frame = CGRectMake(40, 50, 50, 25);
            
        }
        if (i == 4) {
            button.frame = CGRectMake(80, 120, 50, 25);
        }
        if (i == 5) {
            button.frame = CGRectMake(W - 80,110, 50, 25);
        }
        if (i == 6) {
            button.frame = CGRectMake(W - 115, 170, 50, 25);
        }
    }
    
    UIImageView *gifImageView = [[UIImageView alloc] initWithFrame:CGRectMake(80, 125, 40, 40)];
    NSArray *gifArray = [NSArray arrayWithObjects:[UIImage imageNamed:@"shanshuo1"],
                         [UIImage imageNamed:@"shanshuo2"],
                         [UIImage imageNamed:@"shanshuo3"],
                         [UIImage imageNamed:@"shanshuo4"],
                         [UIImage imageNamed:@"shanshuo5"],
                         [UIImage imageNamed:@"shanshuo6"],
                         nil];
    gifImageView.animationImages = gifArray; //动画图片数组
    gifImageView.animationDuration = 2; //执行一次完整动画所需的时长
    gifImageView.animationRepeatCount = 0;  //动画重复次数
    [gifImageView startAnimating];
    [self.imageView addSubview:gifImageView];
    
    
    
    
    
    UITapGestureRecognizer *tap =[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tap:)];
    tap.numberOfTapsRequired = 2;
    [self.view addGestureRecognizer:tap];
}

static CGFloat scale = 1.5;
static bool isBig = NO;
static CGPoint imagePoint;
static CGSize size;
- (void)tap:(UITapGestureRecognizer *)tap{
    
    imagePoint = [tap locationInView:self.imageView];

    if(isBig == NO)
    {
        if(CGRectContainsPoint(self.imageView.bounds, imagePoint)){
            size = self.imageView.size;
            // 向上、向左偏移的距离
            CGFloat top,left;
            top = imagePoint.y * (scale - 1);
            left = imagePoint.x * (scale - 1);
            [UIView animateWithDuration:0.5 animations:^{
                self.imageView.frame = CGRectMake(-left, -top,size.width * scale , size.height * scale);
            }];
            self.scrollView.contentSize = CGSizeMake(size.width * scale , size.height * scale);
            self.scrollView.contentInset = UIEdgeInsetsMake(top, left, -top, -left);
            isBig = YES;
        }

    }else{
        
        [UIView animateWithDuration:.5f animations:^{
            self.scrollView.contentOffset = CGPointMake(0, 0);
            self.imageView.frame = CGRectMake(0, 0, size.width, size.height);
        }];
        self.scrollView.contentInset = UIEdgeInsetsMake(0,0,0,0);
        self.scrollView.contentSize = size;

        isBig = NO;
    }

}

效果图如下

testimage GIF.gif