Ios 我以编程方式创建了UIDatePicker，并让所选日期的UILabel显示，但未能让它正确显示

我试图创建不带故事板的UIDatePicker，让选定日期的UILabel显示出来，但当在模拟器上拾取另一个日期时，标签显示得就像是堆积起来的一样

- (void)viewDidLoad {
    [super viewDidLoad];

    UILabel *myLabel = [[UILabel alloc]initWithFrame:CGRectMake(10, 10,100,100)];
    [self.view addSubview:myLabel];

    UIDatePicker *myPicker = [[UIDatePicker alloc] initWithFrame:CGRectMake(10, 10, 200, 200)];

    myPicker.datePickerMode = UIDatePickerModeDate;

    [myPicker addTarget:self action:@selector(pickerChanged:) forControlEvents:UIControlEventValueChanged];

    [self.view addSubview:myPicker]; 
}


- (void)pickerChanged:(id)sender
{
     NSDateFormatter *df = [[NSDateFormatter alloc] init];   
     UILabel *myLabel = [[UILabel alloc]initWithFrame:CGRectMake(50, 300, 200, 200)];

     df.dateFormat = @"yyyy/MM/dd HH:mm";
     myLabel.text = [df stringFromDate:[sender date]];
     [self.view addSubview:myLabel];   
}

截图如下：

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我是个初学者，找不到解决办法。有人知道如何解决这个问题吗？提前感谢。

这是因为每次日期更改时，您都会创建一个新标签

您需要重用组件，在视图中创建它

- (void)viewDidLoad() {
    ....
   self.myLabel = [[UILabel alloc]initWithFrame:CGRectMake(50, 300, 200, 200)];
   [self.view addSubview:self.myLabel];
}

因此，您可以只设置文本：

- (void)pickerChanged:(id)sender {
    NSDateFormatter *df = [[NSDateFormatter alloc] init];
    df.dateFormat = @"yyyy/MM/dd HH:mm";
    self.myLabel.text = [df stringFromDate:[sender date]]; 
}

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这是因为每次日期更改时，您都要创建一个新标签

您需要重用组件，在视图中创建它

- (void)viewDidLoad() {
    ....
   self.myLabel = [[UILabel alloc]initWithFrame:CGRectMake(50, 300, 200, 200)];
   [self.view addSubview:self.myLabel];
}

因此，您可以只设置文本：

- (void)pickerChanged:(id)sender {
    NSDateFormatter *df = [[NSDateFormatter alloc] init];
    df.dateFormat = @"yyyy/MM/dd HH:mm";
    self.myLabel.text = [df stringFromDate:[sender date]]; 
}

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首先在

viewDidLoad

 UILabel *myLabel = [[UILabel alloc]initWithFrame:CGRectMake(50, 300, 200, 200)];
   [self.view addSubview:self.myLabel];

然后在标签的

PickerChange

self.myLabel.text = [df stringFromDate:[sender date]]; 

---

首先在

viewDidLoad

 UILabel *myLabel = [[UILabel alloc]initWithFrame:CGRectMake(50, 300, 200, 200)];
   [self.view addSubview:self.myLabel];

然后在标签的

PickerChange

self.myLabel.text = [df stringFromDate:[sender date]]; 

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谢谢真的很好吃，谢谢！它真的很管用。