1、UIScrollView下图片的捏合放大和缩小，我们直接用scrollView自带的属性就可以了，这个没什么好说，我们直接贴代码：[plain] view plaincopy//控制器   theScroll=[[UIScrollView alloc] initWithFrame:frame];   theScroll.userInteractionEnabled=YES;   theScroll.maximumZoomScale=2.0;//最大倍率（默认倍率）   theScroll.minimumZoomScale=1.0;//最小倍率（默认倍率）   theScroll.decelerationRate=1.0;//减速倍率（默认倍率）   theScroll.delegate=self;   theScroll.autoresizingMask =UIViewAutoresizingFlexibleLeftMargin|UIViewAutoresizingFlexibleTopMargin|UIViewAutoresizingFlexibleHeight;   [self addSubview:theScroll];      //图片   UIImage *theImageName=[UIImage imageNamed:imageName];   theImage=[[UIImageView alloc] initWithImage:theImageName];   theImage.userInteractionEnabled=YES;   theImage.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin|UIViewAutoresizingFlexibleTopMargin|UIViewAutoresizingFlexibleHeight;   //图片默认作为2倍图处理   theImage.frame=CGRectMake(0, 0, theImageName.size.width/2, theImageName.size.height/2);   [theScroll addSubview:theImage];  另外，我们还要在scrollView的delegate里面设置一下：[plain] view plaincopy#pragma mark -UIScrollView delegate  -(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView  {      return theImage;  }  2、scrollView对图片的双击放大和缩小这里我是通过对双击手势（UIGestureRecognizer）和scrollView的setZoomScale方法来实现放大和缩小。#创建双击手势[plain] view plaincopy//双击手势  UITapGestureRecognizer *doubelGesture=[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(doubleGesture:)];  doubelGesture.numberOfTapsRequired=2;  [theImage addGestureRecognizer:doubelGesture];  [doubelGesture release];  #另外，我们要记录当前的倍率，然后通过判断，是放大还是缩小。当然，还配合捏合的放大和缩小，所以，要在scrollView的delegate里面记录当前倍率，代码：[plain] view plaincopy-(void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale  {      currentScale=scale;  }  #双击手势的方法[plain] view plaincopy#pragma mark -DoubleGesture Action  -(void)doubleGesture:(UIGestureRecognizer *)sender  {            //当前倍数等于最大放大倍数      //双击默认为缩小到原图      if (currentScale==_maxScale) {          currentScale=minScale;          [theScroll setZoomScale:currentScale animated:YES];          return;      }      //当前等于最小放大倍数      //双击默认为放大到最大倍数      if (currentScale==minScale) {          currentScale=_maxScale;          [theScroll setZoomScale:currentScale animated:YES];          return;      }            CGFloat aveScale =minScale+(_maxScale-minScale)/2.0;//中间倍数            //当前倍数大于平均倍数      //双击默认为放大最大倍数      if (currentScale>=aveScale) {          currentScale=_maxScale;          [theScroll setZoomScale:currentScale animated:YES];          return;      }            //当前倍数小于平均倍数      //双击默认为放大到最小倍数      if (currentScale<aveScale) {          currentScale=minScale;          [theScroll setZoomScale:currentScale animated:YES];          return;      }  }