//变量定义
@property(strong,nonatomic)UIImageView *imgView;
@property(strong,nonatomic)UIImage *image;
@property(strong,nonatomic)UIScrollView *bgView ;
float maxScale=2.0f;
BOOL isTwiceTaping;
//-----------------设置UIScrollView-----------------------
//初始化
_bgView = [[UIScrollView alloc] init];
_bgView.frame = [UIScreen mainScreen].bounds;
_bgView.backgroundColor = [UIColor blackColor];
_imgView = [[UIImageView alloc] initWithImage:_image];
[_imgView setContentMode:UIViewContentModeScaleAspectFit];
[_bgView addSubview:_imgView];
// 设置_imgView的位置大小
CGRect frame ;
frame.size.width = bgView.frame.size.width;
frame.size.height =frame.size.width*(_image.size.height/_image.size.width);
_imgView.frame = frame;
_imgView.center=bgView.center;
[[[UIApplication sharedApplication] keyWindow] addSubview:bgView];
// 设置WindowLevel与状态栏平级，起到隐藏状态栏的效果
[[[UIApplication sharedApplication] keyWindow] setWindowLevel:UIWindowLevelStatusBar];
//设置最大放大比例、内容大小和代理
_bgView.maximumZoomScale = maxScale;
_bgView.contentSize=_imgView.frame.size;
_bgView.delegate = self;
//隐藏滚动条
_bgView.showsVerticalScrollIndicator = NO;
_bgView.showsHorizontalScrollIndicator = NO;
//添加双击手势
UITapGestureRecognizer *tapTwice = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapTwiceAction:)];
tapTwice .numberOfTapsRequired = 2;
tapTwice .numberOfTouchesRequired = 1;
[_bgView addGestureRecognizer:tapTwice];
//----------------------双击手势操作----------------------
-(void)tapTwiceAction:(UIGestureRecognizer *)sender{
if(isTwiceTaping){//三次点击不执行
return;
}
isTwiceTaping = YES;
CGFloat newScale;
if(_bgView.zoomScale>1){
newScale=1.0;
}else{
newScale=maxScale;
}
CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[sender locationInView:sender.view]];
[_bgView zoomToRect:zoomRect animated:YES];
//延时做标记判断，使用户点击3次时的单击效果不生效。
[self performSelector:@selector(tapTimes) withObject:nil afterDelay:0.35];
}
-(void)tapTimes{
isTwiceTaping = NO;
}
- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center
{
CGRect zoomRect;
zoomRect.size.height =_bgView.frame.size.height / scale;
zoomRect.size.width =_bgView.frame.size.width / scale;
zoomRect.origin.x = center.x - (zoomRect.size.width /2);
zoomRect.origin.y = center.y - (zoomRect.size.height /2);
return zoomRect;
}
//------------------------ScrollView代理方法----------------------
-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return _imgView;
}
- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
CGFloat xcenter = scrollView.center.x , ycenter = scrollView.center.y;
//目前contentsize的width是否大于原scrollview的contentsize，如果大于，设置imageview中心x点为contentsize的一半，以固定imageview在该contentsize中心。如果不大于说明图像的宽还没有超出屏幕范围，可继续让中心x点为屏幕中点，此种情况确保图像在屏幕中心。
xcenter = scrollView.contentSize.width > scrollView.frame.size.width ? scrollView.contentSize.width/2 : xcenter;
ycenter = scrollView.contentSize.height > scrollView.frame.size.height ? scrollView.contentSize.height/2 : ycenter;
[_imgView setCenter:CGPointMake(xcenter, ycenter)];
}
参考：http://blog.163.com/it__man/blog/static/1371999042013565147299/
