无法接收来自第二视图控制器的回调

Question

我有两个视图控制器。我试着将数据传递到上一视图 - 控制

我已经在我的第二个视图控制器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下面的代码，下面的代码将exectied

- (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，并且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，使用下面的代码。

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

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

但是，当用户从第二视图控制器点击完成按钮，Im不接收在我的第一视图控制器的任何回调。为什么这样？

我已经实现了界面，如下图所示

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

UPDATE：

下面的代码工作

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"); 
} 

但是，如果我尝试通过以下方式，它不工作

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"); 
} 

这是我如何实例化视图控制器。

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，但要解决所有可能性。 您可以检查您的完成按钮操作是否有检查，以确定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"); 
}