write on ios: file does not appear

Question

我想将一些值写入外部文件，并为此使用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是这样的:

NSString *pathInAppDirectory(NSString *fileName)
{
    NSArray *documentDirectories = NSSearchPathForDirectoriesInDomains(NSApplicationDirectory, NSUserDomainMask, YES); 
    NSString *appDir = [documentDirectories objectAtIndex:0];
    return [appDir stringByAppendingPathComponent:fileName];
}

实际上什么都没有发生:如果我想稍后查看文件并希望显示值，则返回null。iPhone模拟器的文件夹中也有一个空文件夹。那里发生了什么，或者更具体地说:没有发生什么?

Answer 1

您需要使用NSDocumentDirectory而不是NSApplicationDirectory。不可能在Application bundle中编写。

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];