iOS 将图片存到本地

将图片以Data形式存到本地，并返回路径

- (NSString *)saveImg:(UIImage *)image withVideoMid:(NSString *)imgName{

    if (!image) {  //防止image不存在，存一个占位图
        image = [UIImage imageNamed:@"posters_default_horizontal"];
    }
    if (!imgName) { //防止imgName不存在,获取一个随机字符串
        imgName = [NSString uuid];
    }
    //png格式
    NSData *imagedata=UIImagePNGRepresentation(image);
    //JEPG格式
    //NSData *imagedata=UIImageJEPGRepresentation(m_imgFore,1.0);

    NSString *savedImagePath = [[PVRSandBoxHelper AlbumVideoImagePath] stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.png", videoMid]];    
    [imagedata writeToFile:savedImagePath atomically:YES];
    return savedImagePath;
}

注： uuid的生成