iphone - 为什么我的 NSMutableDictionary 为空？

Question

这是我的 UIAlertView 委托方法。我不知道为什么 myWordsDictionary 在运行应用程序时为空。（注意：_dailyWords 是一个 NSDictionary 对象，书签是一个 NSString 对象。）

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex 
{
    if (buttonIndex != [alertView cancelButtonIndex]) {
        NSLog(@"Clicked button index !=0");
        // Add the action here
        NSString *documentPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)  lastObject];
        NSString *myWordsPath = [documentPath stringByAppendingPathComponent:@"MyWords.plist"];
        NSMutableDictionary *myWordsDictionary = [[NSMutableDictionary alloc] initWithContentsOfFile:myWordsPath];
        [myWordsDictionary setValue:[_dailyWords objectForKey:bookmarked] forKey:bookmarked];
        [myWordsDictionary writeToFile:myWordsPath atomically:YES];
        NSLog(@"%@", [myWordsDictionary description]);
        [myWordsDictionary release];

    } else {
        NSLog(@"Clicked button index = 0");
        // Add another action here
    }
}

提前致谢。

Answer 1

myWordsPath可能不包含任何有效文件，并且您正在NSMutableDictionary从该路径中存在的文件的内容初始化您的文件。这就是为什么你得到一个空字典。

Answer 2

请尝试此代码..

NSString *documentPath =    [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,    NSUserDomainMask, YES)  objectAtIndex:0];
documentPath =    [documentPath stringByAppendingPathComponent:@"MyWords.plist"]; 
NSMutableDictionary *myWordsDictionary = [[NSMutableDictionary alloc]    initWithContentsOfFile:documentPath];

Answer 3

首先，尝试检查myWordsPath，如果返回 null，您应该查找并找到正确的路径。

其次，你如何生成你的 plist？MyWords.plist必须包含有效格式。如果你不确定，你应该从 XCode 中创建，有 plist 对象。

Answer 4

NSBundle *bundle = [NSBundle mainBundle];
NSString *plistPath = [bundle pathForResource:
                       @"MyWords" ofType:@"plist"];
NSDictionary *dictionary = [[NSDictionary alloc]
                            initWithContentsOfFile:plistPath];