无法从第二个视图控制器接收回调

Question

我有两个视图控制器。我试图将数据传递给前一个视图控制器

我的第二个视图控制器中有以下代码CEPeoplePickerNavigationController

@class CEPeoplePickerNavigationController;
@protocol CEPeoplePickerNavigationControllerDelegate <NSObject>
- (void)previousViewController:(CEPeoplePickerNavigationController *)controller itemToSend:(NSString *)item;
@end


@interface CEPeoplePickerNavigationController : UIViewController <UITableViewDelegate,UITableViewDataSource>{
}
@property (nonatomic, retain) id < CEPeoplePickerNavigationControllerDelegate> peoplePickerDelegate;
@end

当用户点击完成按钮时，将执行以下代码

- (void)doneAction:(id)sender
{
    [self.peoplePickerDelegate previousViewController:self itemToSend:@"From Previous VC"];
    [self dismissViewControllerAnimated:YES completion:nil];
}

在我的第一个视图控制器中，我在头文件中有以下接口，当然我在我的第一个视图控制器中实现了 previousViewController 方法，其中必须接收数据

@interface CallViewViewController : UIViewController<CEPeoplePickerNavigationControllerDelegate>
@end

当我从第一个视图控制器移动到第二个视图控制器时，我使用以下代码。

CEPeoplePickerNavigationController *nextVc = [[CEPeoplePickerNavigationController alloc] init];
    nextVc.peoplePickerDelegate = self;

    [self presentViewController:nextVc animated:YES completion:nil];

但是当用户从第二个视图控制器单击完成按钮时，我在我的第一个视图控制器中没有收到任何回调。为什么会这样？

我已经实现了如下接口，

- (void)previousViewController:(CEPeoplePickerNavigationController *)controller itemToSend:(NSString *)item
{
    NSLog(@"from CEPeoplePickerNavigationController %@",item);
}

更新：

以下代码有效

if ([[CallViewViewController new] respondsToSelector:@selector(previousViewController:item:)]) {
    [self.viewCrtrlDelegate previousViewController:self item:@"Here I am"];
    [self dismissViewControllerAnimated:YES completion:nil];
}
else{
   NSLog(@"Your delegate was properly set");
}

但如果我按照以下方式尝试，它不起作用

if ([[self.viewCrtrlDelegate respondsToSelector:@selector(previousViewController:item:)]) {
    [self.viewCrtrlDelegate previousViewController:self item:@"Here I am"];
    [self dismissViewControllerAnimated:YES completion:nil];
}
else{
   NSLog(@"Your delegate was properly set");
}

这就是我实例化视图控制器的方式。

CEPeoplePickerNavigationController *nextVc = [[CEPeoplePickerNavigationController alloc] init];

    nextVc.viewCrtrlDelegate = self;
    [self presentViewController:nextVc animated:YES completion:nil];

Answer 1

您的代码似乎绝对正确，但要避开所有可能性。 你能检查一下你的完成按钮动作是否检查了该类中的委托方法是否可用？

if ([self.viewCrtrlDelegate respondsToSelector:@selector(previousViewController:item:)]) {
    [self.viewCrtrlDelegate previousViewController:self item:@"Here I am"];
    [self dismissViewControllerAnimated:YES completion:nil];
}
else{
   NSLog(@"Your delegate was properly set");
}