Question

我有一个基于标签的应用，并且每次在标签之间切换时都希望重新加载数据。所以我使用了viewWillAppear:被调用，但数据没有重新加载。这可能是使用大量[NSUserDefault]的结果吗？这是我的代码：

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    [self reloadData];
}

-(void)reloadData {

    //Loading all the data
    totalApples = [[NSUserDefaults standardUserDefaults]integerForKey:@"totalApples"];
    [self setText:[NSString stringWithFormat:@"%.01f", totalApples] withExistingAttributesInLabel:self.applesLabel];

    applesPerSecond = [[NSUserDefaults standardUserDefaults]integerForKey:@"applesPerSecond"];
    [self setText:[NSString stringWithFormat:@"%.01f", applesPerSecond] withExistingAttributesInLabel:self.applesPerSecondLabel];

    applesPerClick = [[NSUserDefaults standardUserDefaults]integerForKey:@"applesPerClick"];
}

Answer 1

使用NSUserDefaults时，最好在写完数据后调用-synchronize。

采用以下示例：

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

[defaults setObject:@100 forKey:@"SomeKey"];

[defaults synchronize]; //This will ensure data is written.

如果您不调用此方法，系统会定期执行此操作。但是，它可能会导致您可能遇到的时间问题。

详细了解NSUserDefaults和此行为here。

<强>更新

我认为这个问题正在失去其背景。以下是您在评论中发布的更新方法。可能值得发布跟进问题，因为这可能不是NSUserDefaults的问题。

至少后人是使用NSUserDefaults写出数据的一个例子。我还更新了您的方法，以便将 priceFarmHands 保存为浮点数，因为正在执行乘法运算。（它之前被写成整数，可能被截断）。

- (void)buyFarmhand {
    farmHands++;
    totalApples -= priceFarmHands;

    if(priceFarmHands < 1000) {
        priceFarmHands = priceFarmHands * 1.35;
    } else if(priceFarmHands < 10000) {
        priceFarmHands = priceFarmHands * 1.25;
    } else {
        priceFarmHands = priceFarmHands * 1.15;
    }

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

    [defaults setFloat:priceFarmHands forKey:@"priceFarmHands"];
    [defaults setInteger:farmHands forKey:@"farmHands"];
    [defaults setDouble:totalApples forKey:@"totalApples"];

    [defaults synchronize];

    [self setText:[NSString stringWithFormat:@"%.f", priceFarmHands] withExistingAttributesInLabel:self priceFarmHandsLabel];
    [self setText:[NSString stringWithFormat:@"%d", farmHands] withExistingAttributesInLabel:self.numberFarmhands];
}

Answer 2

我没有看到你在哪里创建NSUserdefault对象，它应该在reloadData方法中创建，这应该可行：

-(void)reloadData {
    //Loading all the data
    NSUserDefaults *appleData = [NSUserDefaults standardUserDefaults];
    totalApples = [appleData integerForKey:@"totalApples"];
    applesPerSecond = [appleData integerForKey:@"applesPerSecond"];
    applesPerClick = [integerForKey:@"applesPerClick"];

    //Set the labels text
    [self setText:[NSString stringWithFormat:@"%.01f", totalApples] 
                    withExistingAttributesInLabel:self.applesLabel];
    [self setText:[NSString stringWithFormat:@"%.01f", applesPerSecond] 
               withExistingAttributesInLabel:self.applesPerSecondLabel];
}

另外，为了帮助您解决此问题，请将一些日志添加到viewWillAppear：

-(void)viewWillAppear:(BOOL)animated{
    NSLog(@"viewWillAppear called, reloadind data...");
    [super viewWillAppear:animated];
    [self reloadData];
}

NSUserDefaults不会一致地加载数据

2 个答案: