1 //对图片尺寸进行压缩-- 2 -(UIImage*)imageWithImage:(UIImage*)image scaledToSize:(CGSize)newSize 3 { 4     // Create a graphics image context 5     UIGraphicsBeginImageContext(newSize); 6      7     // Tell the old image to draw in this new context, with the desired 8     // new size 9     [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];10     11     // Get the new image from the context12     UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();13     14     // End the context15     UIGraphicsEndImageContext();16     17     // Return the new image.18    return newImage;19 }

//按比例压缩NSData  *imageData = UIImageJPEGRepresentation(self.uploadImage , 0.75);