iOS 图片压缩

• (UIImage )zipNSDataWithImage:(UIImage )sourceImage{
  //进行图像尺寸的压缩
  CGSize imageSize = sourceImage.size;//取出要压缩的image尺寸
  CGFloat width = imageSize.width; //图片宽度
  CGFloat height = imageSize.height; //图片高度
  //1.宽高大于1280(宽高比不按照2来算，按照1来算)
  if (width>1280||height>1280) {
  if (width>height) {
  CGFloat scale = height/width;
  width = 1280;
  height = widthscale;
  }else{
  CGFloat scale = width/height;
  height = 1280;
  width = heightscale;
  }
  //2.宽大于1280高小于1280
  }else if(width>1280||height<1280){
  CGFloat scale = height/width;
  width = 1280;
  height = widthscale;
  //3.宽小于1280高大于1280
  }else if(width<1280||height>1280){
  CGFloat scale = width/height;
  height = 1280;
  width = heightscale;
  //4.宽高都小于1280
  }else{
  }
  UIGraphicsBeginImageContext(CGSizeMake(width, height));
  [sourceImage drawInRect:CGRectMake(0,0,width,height)];
  UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();

  //进行图像的画面质量压缩
  NSData data=UIImageJPEGRepresentation(newImage, 1.0);
  if (data.length>1001024) {
  if (data.length>10241024) {//1M以及以上
  data=UIImageJPEGRepresentation(newImage, 0.1);
  }else if (data.length>5121024) {//0.5M-1M
  data=UIImageJPEGRepresentation(newImage, 0.2);
  }else if (data.length>200*1024) {
  //0.25M-0.5M
  data=UIImageJPEGRepresentation(newImage, 0.3);
  }
  }
  return [UIImage imageWithData:data];
  }