以下代码在 iOS 4.3(也可能是其他版本)下显示了一个奇怪的行为。在此示例中，显示日期设置为 4 Aug 2011 2:31 PM 的 UIDatePicker。 UIDatePicker 下方的 UILabel 显示日期以供引用。下面三个标记为 1、5、10 的 UIButtons 设置 UIDatePicker 上的 minuteInterval。

点击 1 - 在 UIDatePicker 中显示所选日期为 4 Aug 2011 2:31 PM，分钟间隔为 1，这是预期的。

点击 5 - 在 UIDatePicker 中显示所选日期为 4 Aug 2011 2:35 PM，分钟间隔为 5，这是预期的 (有人可能会争辩说时间应该向下舍入，但这不是一个大问题)。

点击 10 - 在 UIDatePicker 中显示所选日期为 4 Aug 2011 2:10 PM，分钟间隔为 10。好的，分钟间隔是正确的, 但选择的时间是 2 点 10 分？人们会期望 2:40(如果向上舍入)或 2:30(如果向下舍入)。

BugDatePickerVC.h

#import <UIKit/UIKit.h>

@interface BugDatePickerVC : UIViewController {
    NSDateFormatter *dateFormatter;
    NSDate *date;
    UIDatePicker *datePicker;
    UILabel *dateL;
    UIButton *oneB;
    UIButton *fiveB;
    UIButton *tenB;
}

- (void) buttonEventTouchDown:(id)sender;

@end

BugDatePickerVC.m

导入“BugDatePickerVC.h”

@implementation BugDatePickerVC

- (id) init
{
    if ( !(self = [super init]) )
    {
        return self;
    }

    dateFormatter = [[NSDateFormatter alloc] init];
    dateFormatter.dateFormat = @"d MMM yyyy h:mm a";

    date = [[dateFormatter dateFromString:@"4 Aug 2011 2:31 PM"] retain];

    // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
    // Date picker
    datePicker = [[UIDatePicker alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 320.0f, 216.0f)];
    datePicker.date = date;
    datePicker.minuteInterval = 1;
    [self.view addSubview:datePicker];

    // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
    // Label with the date.
    dateL = [[UILabel alloc] initWithFrame:CGRectMake(10.0f, 230.0f, 300.0f, 32.0f)];
    dateL.text = [dateFormatter stringFromDate:date];
    [self.view addSubview:dateL];

    // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
    // Button that set the date picker's minute interval to 1.
    oneB = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    oneB.frame = CGRectMake(10.0f, 270.0f, 100.0f, 32.0f);
    oneB.tag = 1;
    [oneB setTitle:@"1" forState:UIControlStateNormal];
    [oneB   addTarget:self
               action:@selector(buttonEventTouchDown:)
     forControlEvents:UIControlEventTouchDown];
    [self.view addSubview:oneB];

    // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
    // Button that set the date picker's minute interval to 5.
    fiveB = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    fiveB.frame = CGRectMake(10.0f, 310.0f, 100.0f, 32.0f);
    fiveB.tag = 5;
    [fiveB setTitle:@"5" forState:UIControlStateNormal];
    [fiveB  addTarget:self
               action:@selector(buttonEventTouchDown:)
     forControlEvents:UIControlEventTouchDown];
    [self.view addSubview:fiveB];

    // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
    // Button that set the date picker's minute interval to 10.
    tenB = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    tenB.frame = CGRectMake(10.0f, 350.0f, 100.0f, 32.0f);
    tenB.tag = 10;
    [tenB setTitle:@"10" forState:UIControlStateNormal];
    [tenB   addTarget:self
               action:@selector(buttonEventTouchDown:)
     forControlEvents:UIControlEventTouchDown];
    [self.view addSubview:tenB];

    return self;
}

- (void) dealloc
{
    [dateFormatter release];
    [date release];
    [datePicker release];
    [dateL release];
    [oneB release];
    [fiveB release];
    [tenB release];

    [super dealloc];
}

- (void) buttonEventTouchDown:(id)sender
{
    datePicker.minuteInterval = [sender tag];
}

最佳答案

好吧，我可以通过使用以下代码将 UIDatePicker 日期值显式设置为四舍五入到分钟间隔的日期来更改行为:

- (void) handleUIControlEventTouchDown:(id)sender
{
    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    // Set the date picker's minute interval.
    NSInteger minuteInterval  = [sender tag];

    // Setting the date picker's minute interval can change what is selected on
    // the date picker's UI to a wrong date, it does not effect the date
    // picker's date value.
    //
    // For example the date picker's date value is 2:31 and then minute interval
    // is set to 10.  The date value is still 2:31, but 2:10 is selected on the
    // UI, not 2:40 (rounded up) or 2:30 (rounded down).
    //
    // The code that follow's setting the date picker's minute interval
    // addresses fixing the date value (and the selected date on the UI display)
    // .  In the example above both would be 2:30.
    datePicker.minuteInterval = minuteInterval;

    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    // Calculate the proper date value (and the date to be selected on the UI
    // display) by rounding down to the nearest minute interval.
    NSDateComponents *dateComponents = [[NSCalendar currentCalendar] components:NSMinuteCalendarUnit fromDate:date];
    NSInteger minutes = [dateComponents minute];
    NSInteger minutesRounded = ( (NSInteger)(minutes / minuteInterval) ) * minuteInterval;
    NSDate *roundedDate = [[NSDate alloc] initWithTimeInterval:60.0 * (minutesRounded - minutes) sinceDate:date];

    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    // Set the date picker's value (and the selected date on the UI display) to
    // the rounded date.
    if ([roundedDate isEqualToDate:datePicker.date])
    {
        // We need to set the date picker's value to something different than
        // the rounded date, because the second call to set the date picker's
        // date with the same value is ignored. Which could be bad since the
        // call above to set the date picker's minute interval can leave the
        // date picker with the wrong selected date (the whole reason why we are
        // doing this).
        NSDate *diffrentDate = [[NSDate alloc] initWithTimeInterval:60 sinceDate:roundedDate];
        datePicker.date = diffrentDate;
        [diffrentDate release];
    }
    datePicker.date = roundedDate;
    [roundedDate release];
}

注意 UIDatePicker 的日期被设置两次的部分。弄清楚这一点很有趣。

有谁知道如何关闭调用 minuteInterval 的动画？点击 5 再点击 10 时的幻影滚动有点难看。

关于ios - UIDatePicker 设置 minuteInterval 时的奇怪行为，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/6948297/