如何从另一个视图控制器更新 UIButton 标签

Question

我有一个 UITabBar 应用程序，它有三个选项卡。第一个选项卡有一个 UIViewController 和一个 UIButton，它显示一个模式 UIViewController 以允许用户选择一个日期。当用户选择他们选择的日期时，我无法更新 UIButton 的标签。

我的主视图控制器 .h / .m

#import <UIKit/UIKit.h>

@interface SearchViewController : UIViewController {
    IBOutlet UIButton *butFromDate;
}

@property (nonatomic, retain) UIButton *butFromDate;

- (IBAction)pickDate:(id)sender;

@end

////////////////////////////////////////////

#import "SearchViewController.h"
#import "SearchDatePickerViewController.h"

@implementation SearchViewController

@synthesize butFromDate;

- (IBAction)pickDate:(id)sender{
    SearchDatePickerViewController *sampleView = [[[SearchDatePickerViewController alloc] init] autorelease];

    [sampleView setModalTransitionStyle:UIModalTransitionStylePartialCurl];
    [self presentModalViewController:sampleView animated:YES];
}

- (void)dealloc {
    [butFromDate release];
    [super dealloc];
}

@end

然后我的模态窗口（带有一个 UIPicker 和几个 UIBarButtons 来取消或保存用户的选择）.h / .m 看起来像：

#import <UIKit/UIKit.h>

@interface SearchDatePickerViewController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource> {
    NSMutableArray *dates;
    IBOutlet UIPickerView *picker;
}

@property (nonatomic, retain) NSMutableArray *dates;
@property (nonatomic, retain) UIPickerView *picker;

- (IBAction)cancelDatePick:(id)sender;
- (IBAction)pickDate:(id)sender;

@end

////////////////////////////////////////////

#import "SearchDatePickerViewController.h"
#import "SearchViewController.h"
#import "AppDelegate.h"
#import "Search.h"

@implementation SearchDatePickerViewController

@synthesize dates, picker;

- (IBAction)cancelDatePick:(id)sender{
    [self dismissModalViewControllerAnimated:YES];
}

- (IBAction)pickDate:(id)sender{
    HolidayCottagesAppDelegate *appDelegate = (HolidayCottagesAppDelegate *)[[UIApplication sharedApplication] delegate];
    SearchViewController *searchView = [SearchViewController alloc];
    appDelegate.currentSearch.fromDate = [dates objectAtIndex:[picker selectedRowInComponent:0]];

    [searchView.butFromDate setTitle:@"HELLO-TEST" forState:UIControlStateNormal];
    [self dismissModalViewControllerAnimated:YES];
}

- (void)viewDidLoad {
    [super viewDidLoad];
    NSDate* curDate = [NSDate date];
    NSCalendar* calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDateComponents* comps = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:curDate];
    NSTimeZone* gmt = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
    dates = [[NSMutableArray alloc] init];

    [comps setTimeZone:gmt];
    [comps setWeekday:7];

    int startCount = comps.week + 1;
    int endCount = (((52 - startCount) + 52) + startCount);

    for (startCount; startCount <= endCount; startCount++){
        NSDate *tDate = [calendar dateFromComponents:comps];
        [dates addObject:tDate];
        [comps setWeek:startCount];
    }
}

// OTHER SHIZZLE HERE BUT NOT REALLY NEEDED TO DISPLAY...

因此，当我单击“保存”按钮时，它会运行 -(void)pickDate: all ok 并关闭模式视图，但不会将 SearchViewController 的 UIButton 标签更新为“HELLO-TEST”。我确定我在这里遗漏了一些简单的东西......

请帮帮我！！

谢谢:)

Answer 1

在您的主视图控制器中，您需要将“self”引用传递给搜索日期选择器视图控制器，然后在搜索日期选择器视图中为主视图控制器设置一个 ivar，并在 pickDate 中使用该引用搜索日期选择器视图的方法。请查看我去年关于这个确切主题的博客文章：

http://www.dosomethinghere.com/2009/10/04/passing-values-and-messages-between-views-on-iphone/

Answer 2

如果您知道如何实现您的自定义委托方法，那就很容易了。只需在选择器视图上使用您想要的参数定义一个委托方法（它假设在您获取值的地方委托），然后在您的 UIViewController 中定义调用此方法并从委托消息中分配值。如果你想要一些例子，我可以给你发一些。

Answer 3

请参阅以下链接。希望它可以帮助某人。

http://www.gisnotes.com/wordpress/2009/08/iphone-note-5-presenting-a-datepicker-as-a-viewcontroller-modally/