ios - 委托(delegate)方法不触发？

Question

就在我以为我对委托(delegate)的工作方式有所了解时，似乎我遗漏了什么。

我已经像这样设置了一个委托(delegate):

ViewControllerA.h

@protocol LoginDelegate <NSObject>

-(void)userLoginSuccessful;

@end
@interface BBLoginViewController : BBBaseViewController
@property (weak, nonatomic) id <LoginDelegate> delegate; 

@end

ViewControllerA.m

-(void)someMethod 
{
    if ([self.delegate respondsToSelector:@selector(userLoginSuccessful)]){
                [self.delegate userLoginSuccessful];
            }
        [self dismissViewControllerAnimated:YES completion:nil];

}

ViewControllerB.m

    #import "ViewControllerA.h"

    @interface ViewControllerB () <UITableViewDataSource, UITableViewDelegate, LoginDelegate>


    -(void)viewWillAppear:(BOOL)animated
    {

        ViewControllerA *loginViewController = [[ViewControllerA alloc]init];
        loginViewController.delegate = self;

    }

#pragma mark - Login Delegate

-(void) userLoginSuccessful
{
  NSLog (@"Delegate fired!");
}

毕竟我的委托(delegate)方法没有触发。我究竟做错了什么？我看了this SO answer并且当检查委托(delegate)不是零时 - 它不是。它设置为 ViewControllerB。

Answer 1

这段代码:

-(void)viewWillAppear:(BOOL)animated
{

    ViewControllerA *loginViewController = [[ViewControllerA alloc]init];
    loginViewController.delegate = self;

}

将创建一个 ViewControllerA 对象，然后(几乎)立即销毁它，这不是您想要的。

无论如何，您可能希望在 prepareForSegue: 方法中设置委托(delegate)...