Question

所以我将3个NSStrings从3个UITextFields保存到属性列表中。这样可以正常工作，但每次我保存新内容时，应用程序都会覆盖之前保存的数据。所以基本上只使用了一个词典，但我希望应用程序每次保存新内容时创建一个新词典，这样就不会删除任何数据。我不知道我怎么能这样做，所以请帮助我！ :)

代码：

NSMutableArray *array = [NSMutableArray arrayWithCapacity:3];
        NSArray *keys = [NSArray arrayWithObjects:@"1",@"2",@"3", nil]; 
        [array addObject:[NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:[NSString stringWithFormat:@"%@",lab.text],[NSString stringWithFormat:@"%@",lab1.text],[NSString stringWithFormat:@"%@",lab2.text], nil] forKeys:keys]]; 
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString *path = [documentsDirectory stringByAppendingPathComponent:@"data.plist"];
        [array writeToFile:path atomically:YES];

Answer 1

使用NSMutableArray添加每个新词典对象，然后将该数组写入data.plist。

Answer 2

你有没有理由为数组分配容量？我只想使用[[NSMutableArray alloc] init]，然后添加你的对象。

另外，我在NSMutableDictionaries中保存NSUserDefaults时遇到问题，所以我最后做的只是将字典保存到文件中

[dict writeToFile:filePath atomically:NO];

和initWithContentsOfFile或initWithContentsOfURL取决于我是否要加载本地或Internet文件。

我应该补充一下，你也可以为NSMutableArray编写ToTile，initWithContentsOf *。

Answer 3

好的我已经知道了：

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

    NSString *documentsDirectory = [paths objectAtIndex:0];

    NSString *path = [documentsDirectory stringByAppendingPathComponent:@"data.plist"];

    NSLog(@"path='%@'",path);

    NSFileManager *nfm = [[NSFileManager alloc] init];
    if([nfm fileExistsAtPath:path])
    {

        // if file exists, get its contents, add more entries and write back

        NSMutableArray *array = [[NSMutableArray alloc] initWithContentsOfFile:path];
        NSArray *keys = [NSArray arrayWithObjects:@"4",@"5",@"6",nil]; 
        [array addObject:[NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:[NSString stringWithFormat:@"%@",lab.text],[NSString stringWithFormat:@"%@",lab1.text],[NSString stringWithFormat:@"%@",lab2.text], nil] forKeys:keys]]; 
        NSLog(@"modified array=%@",array);
        BOOL ok = [array writeToFile:path atomically:YES];
        if(!ok){
            NSLog(@"Unable to write appended file");
            return;
        }

    } else {

        // if file doesn't exist, create a new one

        NSMutableArray *array = [[NSMutableArray alloc] init];
        NSArray *keys = [NSArray arrayWithObjects:@"1",@"2",@"3",nil]; 
        [array addObject:[NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:[NSString stringWithFormat:@"%@",lab.text],[NSString stringWithFormat:@"%@",lab1.text],[NSString stringWithFormat:@"%@",lab2.text], nil] forKeys:keys]]; 
        NSLog(@"new array=%@",array);
        BOOL ok = [array writeToFile:path atomically:YES];
        if(!ok){
            NSLog(@"Unable to write new file");
            return;
        }
    }

将数据保存到plist时创建新字典

3 个答案: