ios - 在ios上写:文件不出现

Question

我想将一些值写入外部文件，并为此目的使用NSDictionary:

NSString *s = @"123456";
NSString *key = @"key";
NSString *file = pathInAppDirectory(@"values");
NSDictionary *dic = [NSDictionary dictionaryWithObject:s forKey:key];
[dic writeToFile:file atomically:YES];

好的，pathInAppDirectory看起来像这样:

NSString *pathInAppDirectory(NSString *fileName)
{
    NSArray *documentDirectories = NSSearchPathForDirectoriesInDomains(NSApplicationDirectory, NSUserDomainMask, YES); 

    NSString *appDir = [documentDirectories objectAtIndex:0];
    return [appDir stringByAppendingPathComponent:fileName];
}

发生的一切完全没有:如果我想稍后再查看文件并显示值，则返回null。再看一下iPhone模拟器的文件夹，也会显示一个空文件夹。那里发生了什么，或更具体地说:什么没有发生？

Answer 1

您需要使用NSDocumentDirectory而不是NSApplicationDirectory。无法写入应用程序捆绑包。

清理示例:

- (NSString *)pathInAppDirectory:(NSString *)fileName {
    NSArray *documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 

    NSString *appDir = [documentDirectories objectAtIndex:0];
    return [appDir stringByAppendingPathComponent:fileName];
}

    NSString *s = @"123456";
    NSString *key = @"key";
    NSDictionary *dic = [NSDictionary dictionaryWithObject:s forKey:key];
    NSString *filePath = [self pathInAppDirectory:@"values"];
    [dic writeToFile:filePath atomically:YES];