裁减图片

+ (NSData *)imageCompatFromImage:(UIImage*)image scaledToSize:(CGSize)newSize

{

    UIGraphicsBeginImageContext(newSize);

    [imagedrawInRect:CGRectMake(0,0,newSize.width,newSize.height)];

    UIImage* newImage =UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    returnUIImageJPEGRepresentation(newImage, 0.5);

}