Question

我有这个代表没有按计划工作，我有这样设置。我想调用函数NSLog(show);我不太确定为什么这不起作用，但与我的其他viewcontroller一起工作。我一定错过了一些小细节。

AccountViewController.h

@protocol AccountViewControllerDelegate;
@interface AccountViewController : UIViewController{

}
@property (nonatomic, assign) id <AccountViewControllerDelegate> accountViewDelegate;
@end

@protocol AccountViewControllerDelegate <NSObject>
- (void)showLabel;
@end

AccountViewController.m

-(IBAction)save:(id)sender {
    [self showLabel];
}

- (void)showLabel {
    if (self.accountViewDelegate) {
        NSLog(@"showlabel");

        [self.accountViewDelegate showLabel];
    }
}

MapViewController.m

-(void)showLabel {
    NSLog(@"SHOW");
}

Answer 1

您没有显示将MapViewController指定为AccountViewController的委托的位置。也许那就是你缺少的东西

//(from somewhere in the MapViewController)

AccountViewController *accountVC = //however you instantiate it (segue, storyboard etc
accountVC.accountViewDelegate = self;

Answer 2

请注意，代表不应该有强烈的参考。

所以使用

@property (unsafe_unretained) id <AccountViewControllerDelegate> accountViewDelegate;

现在MapViewController.m或MapViewController.h符合此协议

@interface MapViewController : UIViewController <AccountViewControllerDelegate>{

}

然后在MapViewController.m中

AccountViewController *accountVC = [[AccountViewController alloc]init]; // initialize it with whatever be like storyboard or nib
accountVC.accountViewDelegate = self;

您的AccountViewController.h文件应如下所示

@protocol AccountViewControllerDelegate <NSObject>
 - (void)showLabel;
@end

@interface AccountViewController : UIViewController{

}
@property (unsafe_unretained) id <AccountViewControllerDelegate> accountViewDelegate;
@end

Answer 3

这是您在不同文件中应该拥有的内容：

<强> AccountViewController.h

请注意，“assign”主要用于NSInteger，CGFloat，BOOL等原语（即，对于非对象的属性）。使用“弱”来指向你的代表而不增加他的保留计数。

@protocol AccountViewControllerDelegate;

@interface AccountViewController : UIViewController
@property (nonatomic, weak) id <AccountViewControllerDelegate> accountViewDelegate;
@end

@protocol AccountViewControllerDelegate <NSObject>
- (void)showLabel;
@end

<强> AccountViewController.m

在这里，通常最好检查代理是否不是nil，以及是否有您要调用的方法。请使用respondToSelector。

-(IBAction)save:(id)sender {
    [self showLabel];
}

- (void)showLabel {
    if (self.accountViewDelegate && [self.accountViewDelegate respondsToSelector:@selector(showLabel)]) {
        NSLog(@"showlabel");

        [self.accountViewDelegate showLabel];
    }
}

<强> MapViewController.h

请务必在此处导入"AccountViewController.h"。

#import "AccountViewController.h"
@interface MapViewController : UIViewController <AccountViewControllerDelegate>
@end

<强> MapViewController.m

将以下内容放在您实例化AccountViewController对象的位置：

//Somewhere
AccountViewController *accountViewController = [[AccountViewController alloc] init];
accountViewController.accountViewDelegate = self;

这是你的委托方法实现：

- (void)showLabel {
    NSLog(@"SHOW");
}

iOS：我不确定，但我的代表并没有像我计划的那样锻炼

3 个答案: