iOS，UIPickerView 以编程方式创建，空 View ，委托(delegate)工作

Question

@大家好，

我在使用 UIPickerView 时遇到了问题。我打算创建一个 View Controller ，它应该允许用户指定第二天。 PickerView 应显示诸如“wed, 1 Dec”、“thu, 2 dec”等字符串 问题是 PickerView 是空的(PickerView 不显示任何字符串)。尽管委托(delegate)方法返回必要的字符串计数和字符串本身。

空 PickerView 的图像 - LINK

下面是我的代码。

.h

@interface OMSDatePickerViewController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource>

@property (nonatomic        ) NSInteger     amountOfDays;
@property (nonatomic        ) CGFloat       cellHeight;

@end

.m

#import "OMSDatePickerViewController.h"

@interface OMSDatePickerViewController () {
    NSMutableArray * dateForChoose;
    NSInteger datePickerActiveIdx;

    UIPickerView *dPicker;
}

@end

- (void)viewDidLoad
{
    NSLog(@"viewDidLoad");

    [super viewDidLoad];
    // Do any additional setup after loading the view.

    dateForChoose = [[NSMutableArray alloc] init];

    dPicker = [[UIPickerView alloc] initWithFrame:CGRectMake(5, 5, 200, 150)];  

    [self.view setFrame: CGRectMake(xPos, yPos, WIN_WIDTH, WIN_HEIGHT)];
    [self.view setAlpha:1.0];
    [self.view setBackgroundColor:[UIColor grayColor]];
    [[self.view layer] setCornerRadius:5.0f];
    [[self.view layer] setBorderWidth:2.0f];
    [[self.view layer] setMasksToBounds:YES];
    [self.view setContentMode:UIViewContentModeScaleToFill];

    // Creating the list of dates
    NSDateFormatter *df = [[NSDateFormatter alloc] init];
    df.dateFormat = @"EEE',' dd MMM";

    [dateForChoose removeAllObjects];

    // Add some data for demo purposes.
    NSDate *curDate = [NSDate date];
    NSString *str;
    for (NSInteger i = 0; i< amountOfDays; i++, curDate = [curDate dateByAddingTimeInterval:60*60*24]) {
        str = [df stringFromDate:curDate];
        [dateForChoose addObject:str];
    }


    [dPicker setDataSource: self];
    [dPicker setDelegate: self];

    dPicker.showsSelectionIndicator = YES;

    [self.view addSubview:dPicker];


    datePickerActiveIdx = 0;

    NSLog(@"%@", dPicker);
}

和委托(delegate)方法

// Number of components.
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
    return 1;
}

// Total rows in our component.
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{
    NSLog(@"numberOfRowsInComponent: %d", [dateForChoose count]);
    return [dateForChoose count];
}

// Display each row's data.
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
    NSString *str = [dateForChoose objectAtIndex: row];
    NSLog(@"%@", [dateForChoose objectAtIndex: row]);
    return [dateForChoose objectAtIndex: row];
}

// Do something with the selected row.
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{
    NSLog(@"You selected this [%2d, %2d]: %@", row, component, [dateForChoose objectAtIndex: row]);
    NSLog(@"count - %d", [dateForChoose count]);
    datePickerActiveIdx = row;
}

有趣的是，当我尝试旋转轮时“didSelectRow”被调用并且总是返回 row == 0 并显示:

[55215:c07] 您选择了这个 [0, 0]:12 月 4 日星期三

[55215:c07] 计数 - 4

有什么想法吗？

补充:如果将相同的代码复制到某些 UIViewController 的内部函数的实现中，则可以很好地工作。例如，它是按钮事件处理程序，按下此按钮会调用代码。

这是什么？？？*

PS:工作日志

[18241:907] viewDidLoad
[18241:907] <UIPickerView: 0x1cd944a0; frame = (5 5; 190 162); layer = <CALayer: 0x1cd94990>>
[18241:907] viewWillAppear
[18241:907] numberOfRowsInComponent: 4
[18241:907] numberOfRowsInComponent: 4
[18241:907] Wed, 04 Dec
[18241:907] Thu, 05 Dec
[18241:907] Fri, 06 Dec
[18241:907] Sat, 07 Dec
[18241:907] viewDidAppear

Answer 1

您可以添加/尝试:

[dPicker setDataSource: self];
[dPicker setDelegate: self];

 dPicker.showsSelectionIndicator = YES;

[self.view addSubview:dPicker];

 [dPicker reloadAllComponents]; // Should reload the data from what I understand