将标题添加到UIPickerView

Question

我使用4个组件创建了UIPickerView。
我可以在UIPickerView中为每个组件添加标题标题吗？

感谢您的任何意见

Answer 1

可以使用的UILabel的UIPicker观点，行之有效上述

Answer 2

我不时使用时间是使标题的第一行中的每一列的另外一个技术：

你需要增加当然行数..

Answer 3

我显示3个组分，然后使用一个UIView示出每个部件的上方为中心的标题（的UILabel）（你可以很容易地修改本更多或更少的组件）：

-(void)labelForDays 
{ 
    NSString *strDay = @"Days"; 
    float lblWidth = self.pickerDayHourMin.frame.size.width/self.pickerDayHourMin.numberOfComponents; 
    float lblXposition = self.pickerDayHourMin.frame.origin.x; 
    float lblYposition = (self.pickerDayHourMin.frame.origin.y); 

    UILabel *lblDay = [[UILabel alloc] initWithFrame:CGRectMake(lblXposition, 
                   lblYposition, 
                   lblWidth, 
                   20)]; 
    [lblDay setText:strDay]; 
    [lblDay setTextAlignment:NSTextAlignmentCenter]; 

    [self.view addSubview:lblDay]; 
} 

然后，标签为第二组分

-(void)labelForHours 
{ 
    NSString *strHours = @"Hours"; 
    float lblWidth = self.pickerDayHourMin.frame.size.width/self.pickerDayHourMin.numberOfComponents; 
    float lblXposition = self.pickerDayHourMin.frame.origin.x; 
    float lblYposition = (self.pickerDayHourMin.frame.origin.y); 

    UILabel *lblHours; 
    if (self.pickerDayHourMin.numberOfComponents ==3) 
    { 
     lblHours = [[UILabel alloc] initWithFrame:CGRectMake((lblXposition + lblWidth), 
                    lblYposition, 
                    lblWidth, 
                    20)]; 
    } 


    [lblHours setText:strHours]; 
    [lblHours setTextAlignment:NSTextAlignmentCenter]; 

    [self.view addSubview:lblHours]; 
} 

最后第三组件的上方居中

-(void)labelForMinutes 
{ 
    NSString *strMinute = @"Minutes"; 
    float lblWidth = self.pickerDayHourMin.frame.size.width/self.pickerDayHourMin.numberOfComponents; 
    float lblXposition = self.pickerDayHourMin.frame.origin.x; 
    float lblYposition = (self.pickerDayHourMin.frame.origin.y); 

    UILabel *lblMinute; 
    if (self.pickerDayHourMin.numberOfComponents ==3) 
    { 
     lblMinute = [[UILabel alloc] initWithFrame:CGRectMake((lblXposition + lblWidth + lblWidth), 
                  lblYposition, 
                  lblWidth, 
                  20)]; 
    } 


    [lblMinute setText:strMinute]; 
    [lblMinute setTextAlignment:NSTextAlignmentCenter]; 

    [self.view addSubview:lblMinute]; 
} 

Answer 4

斯威夫特版本的标签，基于@ greentor的答案一些改进：

var labelTexts = ["Months", "Weeks", "Days", "Hours", "Minutes"] 

override func viewDidAppear(animated: Bool) { 

    let labelWidth = itemPicker.frame.width/CGFloat(itemPicker.numberOfComponents) 

    for index in 0..<labelTexts.count { 
     let label: UILabel = UILabel.init(frame: CGRectMake(itemPicker.frame.origin.x + labelWidth * CGFloat(index), 0, labelWidth, 20)) 
     label.text = labelTexts[index] 
     label.textAlignment = .Center 
     itemPicker.addSubview(label) 
    } 

注意，如果调用viewWillAppear中或更早，因为UIPickerView不会知道在这一点上它的框架尺寸但，这可能无法正常工作。