如何在 [self deniedModalViewControllerAnimated:YES] 之后调用 viewDidLoad； [英] How to call viewDidLoad after [self dismissModalViewControllerAnimated:YES];

问题描述

好的.如果你有两个 viewController 并且你从第一个到第二个执行模态 Segue，那么你可以用 [self deniedModalViewControllerAnimated:YES] 关闭它；它似乎不记得viewDidLoad.我有一个主页 (viewController)，然后是一个选项页面，我希望在您更改选项时更新主页.当我只做了两个模态转场(一个前进，一个后退)时，这很有效，但这似乎是非结构化的，可能会导致大型项目中的代码混乱.

Okay. If you have two viewControllers and you do a modal Segue from the first to the second, then you dismiss it with [self dismissModalViewControllerAnimated:YES]; it doesn't seem to recall viewDidLoad. I have a main page (viewController), then a options page of sorts and I want the main page to update when you change an option. This worked when I just did a two modal segues (one going forward, one going back), but that seemed unstructured and may lead to messy code in larger projects.

我听说过push segues.他们好些了吗?

I have heard of push segues. Are they any better?

谢谢.我感谢任何帮助:)

Thanks. I appreciate any help :).

推荐答案

那是因为 UIViewController 已经加载到内存中了.但是，您可以使用 viewDidAppear:.

That's because the UIViewController is already loaded in memory. You can however use viewDidAppear:.

或者，您可以使推送视图控制器成为推送视图控制器的代理，并在推送控制器退出屏幕时通知它更新.

Alternatively, you can make the pushing view controller a delegate of the pushed view controller, and notify it of the updates when the pushed controller is exiting the screen.

后一种方法的好处是不需要重新运行 viewDidAppear: 的整个主体.例如，如果您只更新表格行，为什么要重新渲染整个内容?

The latter method has the benefit of not needing to re-run the entire body of viewDidAppear:. If you're only updating a table row, for example, why re-render the whole thing?

这里有一个使用委托的简单示例，仅供您参考:

Just for you, here is a quick example of using delegates:

#import <Foundation/Foundation.h>

// this would be in your ModalView Controller's .h
@class ModalView;

@protocol ModalViewDelegate

- (void)modalViewSaveButtonWasTapped:(ModalView *)modalView;

@end

@interface ModalView : NSObject

@property (nonatomic, retain) id delegate;

@end

// this is in your ModalView Controller's .m
@implementation ModalView

@synthesize delegate;

- (void)didTapSaveButton
{
    NSLog(@"Saving data, alerting delegate, maybe");

    if( self.delegate && [self.delegate respondsToSelector:@selector(modalViewSaveButtonWasTapped:)])
    {
        NSLog(@"Indeed alerting delegate");

        [self.delegate modalViewSaveButtonWasTapped:self];
    }
}

@end

// this would be your pushing View Controller's .h
@interface ViewController : NSObject <ModalViewDelegate>

- (void)prepareForSegue;

@end;

// this would be your pushing View Controller's .m
@implementation ViewController

- (void)prepareForSegue
{
    ModalView *v = [[ModalView alloc] init];

    // note we tell the pushed view that the pushing view is the delegate
    v.delegate = self;

    // push it

    // this would be called by the UI
    [v didTapSaveButton];
}

- (void)modalViewSaveButtonWasTapped:(ModalView *)modalView
{
    NSLog(@"In the delegate method");
}

@end

int main(int argc, char *argv[]) {
    @autoreleasepool {

        ViewController *v = [[ViewController alloc] init];

        [v prepareForSegue];
    }
}

输出:

2012-08-30 10:55:42.061 Untitled[2239:707] Saving data, alerting delegate, maybe
2012-08-30 10:55:42.064 Untitled[2239:707] Indeed alerting delegate
2012-08-30 10:55:42.064 Untitled[2239:707] In the delegate method

示例在 CodeRunner 中针对 OS X 运行，我与之零从属关系.

Example was ran in CodeRunner for OS X, whom I have zero affiliation with.

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