iPhone：copyItemAtPath出错

Question

我正在尝试将文件从一个文件夹复制到文档目录中的另一个文件夹，如下所示：

    - (void)saveFile:(NSString *)folderPath
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0]; 
    NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:@"destination.png"];

    NSError *error = nil;
    NSString *srcPath = [folderPath stringByAppendingPathComponent:@"filename.png"];


    BOOL success = [[NSFileManager defaultManager] copyItemAtPath:srcPath toPath:documentsDirectory error:&error];
    if (error)
    {
        NSLog(@"%@",error);
    }

    if (success == YES)
    {
        NSLog(@"Copied");
    }
    else
    {
        NSLog(@"Not Copied");
    }
}

当我记录错误时，它会给我以下消息：

Error Domain=NSCocoaErrorDomain Code=516 "The operation couldn’t be completed. (Cocoa error 516.)" UserInfo=0x9d665a0 {NSUserStringVariant=(
    Move
), NSFilePath=/Users/username/Library/Application Support/iPhone Simulator/5.1/Applications/BC37C9D7-7995-47C1-8131-2B07BADCBECB/Documents/foldername/B713320C-2CA0-4FD3-93F6-71D76B102B83/src.png, NSDestinationFilePath=/Users/username/Library/Application Support/iPhone Simulator/5.1/Applications/BC37C9D7-7995-47C1-8131-2B07BADCBECB/Documents, NSUnderlyingError=0x9d41c60 "The operation couldn’t be completed. File exists"}

Answer 1

问题1： 出现此问题的原因是，该目录已包含具有相同文件名的文件。

您应该检查文件夹中是否存在文件：

- (void)saveFile:(NSString *)folderPath
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0]; 
    NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:@"destination.png"];

    NSError *error = nil;
    NSString *srcPath = [folderPath stringByAppendingPathComponent:@"filename.png"];

    if ([[NSFileManager defaultManager] fileExistsAtPath:dataPath])
    {
        //removing file
        if (![[NSFileManager defaultManager] removeItemAtPath:dataPath error:&error])
        {
            NSLog(@"Could not remove old files. Error:%@",error);
        }
    }
    BOOL success = [[NSFileManager defaultManager] copyItemAtPath:srcPath toPath:dataPath error:&error];
    if (success == YES)
    {
        NSLog(@"Copied");
    }
    else
    {
        NSLog(@"Not Copied %@", error);
    }
}

问题2： 您必须提供文件名而不是目录。

替换：

BOOL success = [[NSFileManager defaultManager] copyItemAtPath:srcPath toPath:documentsDirectory error:&error];

使用：

BOOL success = [[NSFileManager defaultManager] copyItemAtPath:srcPath toPath:dataPath error:&error];

Answer 2

copyItemAtPath：由于该文件已存在于该位置，因此发出错误。所以你应该在复制文件之前这样做。

if ([[NSFileManager defaultManager] fileExistsAtPath: srcPath])
        [[NSFileManager defaultManager] removeItemAtPath: srcPath error:nil];

Answer 3

替换此行：

BOOL success = [[NSFileManager defaultManager] copyItemAtPath:srcPath toPath:documentsDirectory error:&error];

使用：

BOOL success = [[NSFileManager defaultManager] copyItemAtPath:srcPath toPath:dataPath error:&error];