ios 图片拖拽，捏，双击放大缩小，以及保存到相册

图片拖拽，放大缩小原来是可以不用自己写算法的，直接用UIscrollView即可实现。

保存相册就比较简单了。

比较麻烦的地方：

捏，双击等动作形成的放大、缩小效果需要准确定位。

h文件：

////  DetailPopStarView.h//  Gukw//#import <UIKit/UIKit.h>#import "AsyncImageView.h"@interface DetailPopStarView : UIView<UIScrollViewDelegate>@property (nonatomic) NSString *url;@property (nonatomic) AsyncImageView *imgView;@property (nonatomic) CGFloat width;@property (nonatomic) CGFloat height;@property (nonatomic) BOOL isTwiceTaping;@property (nonatomic) BOOL isDoubleTapingForZoom;@property (nonatomic) CGFloat currentScale;@property (nonatomic) CGFloat offsetY;@property (nonatomic) UIScrollView *scrollView;@property (nonatomic) UIActivityIndicatorView *activityIndicatorView;@property (nonatomic) CGFloat touchX;@property (nonatomic) CGFloat touchY;-(void) draw;@end

m文件：

////  DetailPopStarView.m////#import "DetailPopStarView.h"#import "commonFunctions.h"#define kScreenWidth  320.0#define kScreenHeight  460.0#define kMaxZoom 3.0@implementation DetailPopStarView@synthesize imgView = _imgView;@synthesize url = _url;@synthesize width = _width;@synthesize height = _height;@synthesize activityIndicatorView = _activityIndicatorView;@synthesize isTwiceTaping = _isTwiceTaping;@synthesize scrollView = _scrollView;@synthesize currentScale = _currentScale;@synthesize isDoubleTapingForZoom = _isDoubleTapingForZoom;@synthesize  touchX = _touchX;@synthesize  touchY = _touchY;@synthesize offsetY = _offsetY;- (id)initWithFrame:(CGRect)frame{    self = [super initWithFrame:frame];    if (self) {        // Initialization code    }    return self;}// Only override drawRect: if you perform custom drawing.// An empty implementation adversely affects performance during animation.- (void)drawRect:(CGRect)rect{}- (void) draw{    self.frame = CGRectMake(0, 0, kScreenWidth, kScreenHeight);    self.backgroundColor = [UIColor blackColor];    self.alpha = 0.0;    _scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, kScreenWidth, kScreenHeight)];    [self addSubview:_scrollView];    _scrollView.delegate = self;    _scrollView.maximumZoomScale = 5.0;    CGFloat ratio = _width/_height*kScreenHeight/kScreenWidth;    CGFloat min = MIN(ratio, 1.0);    _scrollView.minimumZoomScale = min;        CGFloat height = _height /_width * kScreenWidth;    _imgView = [[AsyncImageView alloc] initWithFrame:CGRectMake(_scrollView.contentOffset.x+100, _scrollView.contentOffset.y+230, 10, 10)];    [_imgView loadImage:_url];        CGFloat y = (kScreenHeight - height)/2.0;    _offsetY = 0.0-y;    _scrollView.contentSize = CGSizeMake(kScreenWidth, height);    [_scrollView addSubview:_imgView];    _scrollView.contentOffset = CGPointMake(0, 0.0-y);        [UIView animateWithDuration:0.6        delay:0.0        options: UIViewAnimationCurveEaseOut        animations:^{            _imgView.frame = CGRectMake(0, 0, kScreenWidth, height);              self.alpha = 1.0;        }         completion:^(BOOL finished){        }    ];            UITapGestureRecognizer *tapImgView = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapImgViewHandle)];    tapImgView.numberOfTapsRequired = 1;    tapImgView.numberOfTouchesRequired = 1;    [self addGestureRecognizer:tapImgView];        UITapGestureRecognizer *tapImgViewTwice = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapImgViewHandleTwice:)];    tapImgViewTwice.numberOfTapsRequired = 2;    tapImgViewTwice.numberOfTouchesRequired = 1;    [self addGestureRecognizer:tapImgViewTwice];    [tapImgView requireGestureRecognizerToFail:tapImgViewTwice];            UITapGestureRecognizer *saveTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(saveTapHandler)];    UIButton *save = [commonFunctions generateImage:@"save-pic-button.png" hover:@"save-pic-button-hover.png" withX:245 withY:420];    [save addGestureRecognizer:saveTap];    [self addSubview:save];        _activityIndicatorView = [commonFunctions generateActivityIndicatorView];    [self addSubview:_activityIndicatorView];}#pragma mark - UIscrollViewDelegate zoom-(void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale{    _currentScale = scale;    NSLog(@"current scale:%f",scale);}-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{    return _imgView;}-(void)scrollViewDidZoom:(UIScrollView *)scrollView{    //当捏或移动时，需要对center重新定义以达到正确显示未知    CGFloat xcenter = scrollView.center.x,ycenter = scrollView.center.y;    NSLog(@"adjust position,x:%f,y:%f",xcenter,ycenter);    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;    //双击放大时，图片不能越界，否则会出现空白。因此需要对边界值进行限制。    if(_isDoubleTapingForZoom){          NSLog(@"taping center");        xcenter = kMaxZoom*(kScreenWidth - _touchX);        ycenter = kMaxZoom*(kScreenHeight - _touchY);        if(xcenter > (kMaxZoom - 0.5)*kScreenWidth){//放大后左边超界            xcenter = (kMaxZoom - 0.5)*kScreenWidth;        }else if(xcenter <0.5*kScreenWidth){//放大后右边超界            xcenter = 0.5*kScreenWidth;        }        if(ycenter > (kMaxZoom - 0.5)*kScreenHeight){//放大后左边超界            ycenter = (kMaxZoom - 0.5)*kScreenHeight +_offsetY*kMaxZoom;        }else if(ycenter <0.5*kScreenHeight){//放大后右边超界            ycenter = 0.5*kScreenHeight +_offsetY*kMaxZoom;        }        NSLog(@"adjust postion sucess, x:%f,y:%f",xcenter,ycenter);            }    [_imgView setCenter:CGPointMake(xcenter, ycenter)];}#pragma mark - tap-(void)tapImgViewHandle{    NSLog(@"%d",_isTwiceTaping);    if(_isTwiceTaping){        return;    }    NSLog(@"tap once");        [UIView animateWithDuration:0.6        delay:0.0        options: UIViewAnimationCurveEaseOut        animations:^{            _imgView.frame = CGRectMake(_scrollView.contentOffset.x+100, _scrollView.contentOffset.y+230, 10, 10);              self.alpha = 0.0;        }         completion:^(BOOL finished){            [self removeFromSuperview];        }    ];        }-(IBAction)tapImgViewHandleTwice:(UIGestureRecognizer *)sender{    _touchX = [sender locationInView:sender.view].x;    _touchY = [sender locationInView:sender.view].y;    if(_isTwiceTaping){        return;    }    _isTwiceTaping = YES;        NSLog(@"tap twice");        if(_currentScale > 1.0){        _currentScale = 1.0;        [_scrollView setZoomScale:1.0 animated:YES];    }else{        _isDoubleTapingForZoom = YES;        _currentScale = kMaxZoom;        [_scrollView setZoomScale:kMaxZoom animated:YES];    }    _isDoubleTapingForZoom = NO;    //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(twiceTaping) withObject:nil afterDelay:0.65];    NSLog(@"sdfdf");}-(void)twiceTaping{    NSLog(@"no");    _isTwiceTaping = NO;}-(void) saveTapHandler{    if([_activityIndicatorView isAnimating]){        return;    }    [_activityIndicatorView startAnimating] ;    UIImageWriteToSavedPhotosAlbum(_imgView.image, self, @selector(imageSavedToPhotosAlbum: didFinishSavingWithError: contextInfo:), nil);}#pragma mark - savePhotoAlbumDelegate- (void)imageSavedToPhotosAlbum:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *) contextInfo {      NSString *message;      NSString *title;          [_activityIndicatorView stopAnimating];    if (!error) {        title = @"恭喜";          message = @"成功保存到相册";      } else {          title = @"失败";          message = [error description];      }      UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title message:message delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil];     [alert show];}@end