無法接收來自第二視圖控制器的回調

Question

我有兩個視圖控制器。我試着將數據傳遞到上一視圖 - 控制

我已經在我的第二個視圖控制器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 

當用戶點擊完成按鈕下面的代碼，下面的代碼將exectied

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

在我的第一個視圖控制器中，我在頭文件中有以下接口，並且我在我的第一個視圖控制器中實現了previousViewController方法，其中必須接收數據

@interface CallViewViewController : UIViewController<CEPeoplePickerNavigationControllerDelegate> 
@end 

當我從第一個視圖控制器移動到第二個視圖控制器時，使用下面的代碼。

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

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

但是，當用戶從第二視圖控制器點擊完成按鈕，Im不接收在我的第一視圖控制器的任何回調。爲什麼這樣？

我已經實現了界面，如下圖所示

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

UPDATE：

下面的代碼工作

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，如果我嘗試通過以下方式，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"); 
} 

這是我如何實例化視圖控制器。

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

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

Answer 1

您的代碼似乎絕對正確，但要解決所有可能性。 您可以檢查您的完成按鈕操作是否有檢查，以確定該類中的委託方法是否可用？

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"); 
}