保存图片到包中

- (void)savePicturefromurl:(NSString *)url path:(NSString *)path imgName:(NSString *)imgName
{
    UIImage *img=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:url]]];
     if(path==nil)
    {
        path = [[[NSBundle mainBundle] bundlePath] stringByAppendingPathComponent:imgName];
    }
    [UIImagePNGRepresentation(image) writeToFile:path atomically:YES];
}