压缩 UIImage
UIImage+Scale.h
@interface UIImage (Scale)
//等比率缩放

• (UIImage *)scaleImageToScale:(float)scale;

//自定长宽

• (UIImage*)scaleImageToSize:(CGSize)size;
  @end

UIImage+Scale.m

import "UIImage+Scale.h"

@implementation UIImage (Scale)

//等比率缩放

• (UIImage *)scaleImageToScale:(float)scale
  {
  UIGraphicsBeginImageContext(CGSizeMake(self.size.width * scale, self.size.height * scale)); [self drawInRect:CGRectMake(0, 0, self.size.width * scale, self.size.height * scale)];
  UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext();
  return scaledImage;
  }
  //自定长宽
• (UIImage)scaleImageToSize:(CGSize)size{
  UIGraphicsBeginImageContext(size);
  [self drawInRect:CGRectMake(0, 0, size.width, size.height)];
  UIImage scaledImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext();
  return scaledImage;
  }

@end