Question

我的UIViewController里面有UIDatePicker。我在标题类中将UIDatePicker与IBOutlet属性相关联，因为我在我的应用中使用了故事板：

#import <UIKit/UIKit.h>
@protocol CreationDateDelegate <NSObject>
@optional
    -(void)selectedDateIs:(NSString*)dateValue;
@end

@interface SelectCreationDateViewController : UIViewController
{
    IBOutlet UIDatePicker *datePicker;
}
@property (nonatomic,assign)id<CreationDateDelegate>creationDateDelegate;
@property (nonatomic,retain) IBOutlet UIDatePicker *datePicker;

@end

--- .m -----

#import "SelectCreationDateViewController.h"
@interface SelectCreationDateViewController ()
{
    NSString *dateFromString;
}
@end

@implementation SelectCreationDateViewController
@synthesize creationDateDelegate,datePicker;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) 
    {
    }
    return self;
}

- (void)viewDidLoad
{   
    self.title = @"Select creation date";
    [super viewDidLoad];

    [datePicker setHidden:NO];
    datePicker.timeZone = [NSTimeZone localTimeZone];
    [datePicker setDatePickerMode:UIDatePickerModeDate];

    [datePicker addTarget:self action:@selector(changeValueOfDatePicker:) forControlEvents:UIControlEventValueChanged];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(void)viewWillDisappear:(BOOL)animated{
    NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
    NSString *dateFromString = [formatter stringFromDate:datePicker.date];
    [self.creationDateDelegate selectedDateIs:dateFromString];
}

-(void)changeValueOfDatePicker:(id)sender{
    NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
    dateFromString = [formatter stringFromDate:datePicker.date];
    [self.creationDateDelegate selectedDateIs:dateFromString];
    NSLog(@"Date from string value equal %@",dateFromString);
}
@end

为什么每次更改DatePicker返回值的值都不会改变？有任何想法吗？另外，如果我在代码中犯了任何错误，请告诉我。

Answer 1

通过添加此行代码修复，

仅在您使用iOS7时 - 在method（void）viewDidLoad方法

中

[self.datePicker setDate:[NSDate date] animated:YES];

Answer 2

也设置一些日期格式

 -(void)changeValueOfDatePicker:(id)sender{

        NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
        [formatter setDateFormat:@"yyyy-MM-dd HH:mm"];

        dateFromString = [formatter stringFromDate:datePicker.date];
        [self.creationDateDelegate selectedDateIs:dateFromString];
        NSLog(@"Date from string value equal %@",dateFromString);
    }

UIDatePicker不会更改值

2 个答案: