ios - 每次保存新数据时 Plist 都会重写旧数据

Question

我有一个简单的 Objective-C 程序，我在其中将用户输入的数据保存在 plist 中。但是当我尝试在我的 plist 中保存多个数据时，它会重写旧数据，我只能在我的 plist 中获取一个数据，即用户输入的最后一个数据。下面是我保存数据的代码-

- (IBAction)savedata:(id)sender
{

    NSError *error;
    NSString *arr= [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

   arr=[arr stringByAppendingPathComponent:@"datalist.plist"];

    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSMutableArray *valuearray = [[NSMutableArray alloc]init];
    NSMutableDictionary *dict = [[NSMutableDictionary alloc]init];
    [dict setValue:_nametextfield.text forKey:@"NAME"];
    [valuearray addObject:dict];

    if ([fileManager fileExistsAtPath:arr])
    {
        NSLog(@"FILE EXIST");
        self.bundle = [[NSBundle mainBundle]pathForResource:@"datalist" ofType:@"plist" ];//NSString *bundle = [[NSBundle mainBundle] pathForResource:@”data” ofType:@”plist”];
        NSLog(@"%@",_bundle);

        [fileManager copyItemAtPath:_bundle toPath: arr error:&error];

        [valuearray writeToFile:arr atomically:YES];
        NSLog(@"%@",arr);

        //6
    }
    else
    {
        NSLog(@"FILE DOESN'T EXIST");
        [valuearray writeToFile:arr atomically:YES];
    }


}

这是我获取的数据 -

- (IBAction)fetchdata:(id)sender
{
    NSString *arr= [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

    arr=[arr stringByAppendingPathComponent:@"datalist.plist"];
    if ([[NSFileManager defaultManager]fileExistsAtPath:arr])
    {
        NSArray *dict=[NSArray arrayWithContentsOfFile:arr];
        NSLog(@"%@",dict);

    }

}

现在我只能检索最后输入的数据，我不知道为什么会导致这么多问题。请有人帮我解决这个问题。我还附上了我的主包的屏幕截图。

Answer 1

用这个替换保存部分 -

- (IBAction)savedata:(id)sender
{
    NSError *error;
    NSString *arr= [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

    arr=[arr stringByAppendingPathComponent:@"datalist.plist"];

    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSMutableArray *valuearray = [[NSMutableArray alloc]init];
    NSMutableDictionary *dict = [[NSMutableDictionary alloc]init];
    [dict setValue:_titletextfield.text forKey:@"NAME"];
    [valuearray addObject:dict];

    if ([fileManager fileExistsAtPath:arr])
    {
        NSLog(@"FILE EXIST");
        //self.bundle = [[NSBundle mainBundle]pathForResource:@"datalist" ofType:@"plist" ];//NSString *bundle = [[NSBundle mainBundle] pathForResource:@”data” ofType:@”plist”];
        // NSLog(@"%@",_bundle);

        //[fileManager copyItemAtPath:_bundle toPath: arr error:&error];
        NSMutableArray *valuearray = [[NSMutableArray alloc]initWithContentsOfFile:arr];
        if (dict.count)
        {
            [valuearray addObject:dict];
        }
        else
        {
            NSLog(@"data not retrieved");
        }

        [valuearray writeToFile:arr atomically:YES];
        NSLog(@"%@",arr);

        //6
    }
    else
    {
        NSLog(@"FILE DOESN'T EXIST");
        [valuearray writeToFile:arr atomically:YES];
    }

    UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"sucess" message:@"successfully saved" delegate:self cancelButtonTitle:@"ok" otherButtonTitles: nil];
    [alert show];
    [self.navigationController popToRootViewControllerAnimated:YES];
}

感谢@rmaddy。