NSFileManager未保存

Question

我一直在尝试使用NSFileManager将图片缓存到沙盒应用程序的缓存目录中。不幸的是，我的代码似乎不能工作。

- (BOOL)saveImageToCacheFolder
{
    NSFileManager *filemgr = [NSFileManager defaultManager];
    NSString *cachePath = [[[filemgr URLsForDirectory:NSCachesDirectory inDomains:NSUserDomainMask] lastObject] absoluteString];
    NSString *fullpath = [cachePath stringByAppendingPathComponent:@"test.jpg"];
    NSURL *imageURL = [FlickrFetcher urlForPhoto:self.photoData format:FlickrPhotoFormatLarge];
    NSData *imageData = [NSData dataWithContentsOfURL:imageURL];

    BOOL success = false;
    if (imageData != nil) {
        success = [imageData writeToURL:[NSURL URLWithString:fullpath] atomically:true];
        if (!success) NSLog(@"Did Not Managed to save the image");
    }
    return success;
}

这就是我想要做的。首先，获取默认的NSFileManager。其次，获取我的应用程序缓存目录的相对路径。第三，附加我的文件名(这里我现在只写了test )。第四，将我的图像转换为NSData。第四，将NSData对象写入指定的路径。

edit:添加if语句，用于检查imageData是否为空

Answer 1

试试这个：

NSArray *myPathList = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString *cachePath    = [myPathList  objectAtIndex:0];
NSString *fullpath = [cachePath stringByAppendingPathComponent:@"test.jpg"];

NSURL *imageURL = [FlickrFetcher urlForPhoto:self.photoData format:FlickrPhotoFormatLarge];
NSData *imageData = [NSData dataWithContentsOfURL:imageURL];

if (imageData != nil) {
    success = [imageData writeToURL:[NSURL fileURLWithPath:fullpath] atomically:YES];
    if (!success) NSLog(@"Did Not Managed to save the image");
}