Question

我遇到了显示字符串的标签问题。

所以，基本上，我有一个函数- (void) didFinishUpdatesSuccessfully。如果正在调用此函数，则表示操作已成功完成。它会创建一个时间戳并将其存储到NSUserDefaults。所有这一切都像一个魅力.. 这是功能：

    - (void) didFinishUpdatesSuccessfully {

        // Create formatted date string
        NSDate *currDate = [NSDate date];
        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
        [dateFormatter setDateFormat:@"dd/MM/YYYY - hh:mm:ss a"];
        NSString *dateString = [dateFormatter stringFromDate:currDate];

        NSMutableString* lastUpdated;
        lastUpdated = [[NSMutableString stringWithFormat:@"%@",dateString] retain];
        NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
        [defaults setObject:lastUpdated forKey:@"lastUpdated"];
        [defaults synchronize];

        //--- Alert dialog
        NSString *title;
        title = @"All the latest hotspots have now been saved!";
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle: title
                                                    message: lastUpdated
                                                   delegate: nil
                                          cancelButtonTitle: [FileUtils appResourceForKey:@"HOTSPOT_GENERAL_BUTTON_TITLE_OK"]
                                          otherButtonTitles: nil];

// ------------------------
//Create label
    UILabel *UpDLabel = [[UILabel alloc] initWithFrame:CGRectMake(50, 205, 250, 100)];
    UpDLabel.backgroundColor = [UIColor clearColor]; // [UIColor brownColor];
    UpDLabel.font = [UIFont fontWithName:@"Helvetica" size: 11.0];
    UpDLabel.shadowColor = [UIColor whiteColor];
    UpDLabel.shadowOffset = CGSizeMake(1,1);
    UpDLabel.textColor = [UIColor blackColor];
    UpDLabel.textAlignment = UITextAlignmentRight; // UITextAlignmentCenter, UITextAlignmentLeft
    UpDLabel.lineBreakMode = UILineBreakModeWordWrap;
    NSString *lupdate   = [NSString stringWithFormat: @"Last Update: %@", lastUpdated];

    UpDLabel.text = lupdate;

    [self.view addSubview:UpDLabel];

    [UpDLabel release];
// ------------------------     


        [dateFormatter release];
        [lastUpdated release];
        [alert show];
        [alert release];

        //--- remove indicator view
        [self indicatorViewShow:NO];

    }

正在显示带有日期字符串的标签。它会覆盖自己，但似乎保留了前一个字符串，因此它实际上看起来只是在前一个字符串之上添加了另一个层。换句话说，如果我执行- (void) didFinishUpdatesSuccessfully 3次，它会在彼此的顶部显示3个日期字符串，这看起来很糟糕......

我做错了什么？

干杯扬

Answer 1

每次调用didFinishUpdatesSuccesfully方法时，您都在重新创建并重新添加UpDLabel。

相反，使UpDLabel成为您班级的属性：

UILabel *UpDLabel
@property (nonatomic, retain) UILabel *upDLabel

在didFinishUpdatesSuccesfully的代码中执行：

if (!self.upDLabel) {
    self.upDLabel = [[[UILabel alloc] initWithFrame:CGRectMake(50, 205, 250, 100)] autorelease];
    self.upDLabel.backgroundColor = [UIColor clearColor]; // [UIColor brownColor];
    self.upDLabel.font = [UIFont fontWithName:@"Helvetica" size: 11.0];
    self.upDLabel.shadowColor = [UIColor whiteColor];
    self.upDLabel.shadowOffset = CGSizeMake(1,1);
    self.upDLabel.textColor = [UIColor blackColor];
    self.upDLabel.textAlignment = UITextAlignmentRight; // UITextAlignmentCenter, UITextAlignmentLeft
    self.upDLabel.lineBreakMode = UILineBreakModeWordWrap;

    [self.view addSubview:self.upDLabel];

}

NSString *lupdate   = [NSString stringWithFormat: @"Last Update: %@", lastUpdated];
self.upDLabel.text = lupdate;

Answer 2

这是因为您不断向视图添加子视图，而不是仅仅将新文本添加到UILabel中。设置UILabel一次，然后只需使用UpDLabel.text = lupdate更改文本。

乔

Answer 3

为什么不在- viewDidLoad方法中创建UILabel呢？使标签成为类的属性，然后在- viewDidLoad上创建标签，然后更新- didFinishUpdatesSuccessfully内标签内的字符串。它会更方便。

字符串/标签问题

3 个答案: