把图片写入沙盒文件（具体还在研究）

先以时间命名

_uploadImageName = [[NSString alloc]initWithFormat:@"picture_%0.f.png",[[NSDate date] timeIntervalSince1970]];    [self saveImage:_myImg withName:_uploadImageName];

- (void) saveImage:(UIImage *)currentImage withName:(NSString *)imageName{    NSData *imageData = UIImageJPEGRepresentation(currentImage, 0.5);    // 获取沙盒目录    NSString * path =  [_filePath stringByAppendingPathComponent:imageName];    // 将图片写入文件    [imageData writeToFile:path atomically:NO];}

会用到一些图片上传接口  

_filePath  那些要用到第三方