实现委托以启用模态视图将数据传回UIViewController [英] Implementing a delegate to enable a modal view to pass data back to a UIViewController

问题描述

我正在尝试实现一个委托以启用模态视图将数据传回给UIViewController。

我有两个视图控制器，我的主要UIViewController和模态。使用下面的代码，[delegate translationTextEntered：@Test];不影响主屏幕（即'translationTextEntered'从不被调用）

我的主控制器

包含当模态具有用户值时要调用的方法：

MainViewController.h

   - （void）translationTextEntered :( NSString *）txt; 
  

MainViewController.m

   - （void）translationTextEntered :( NSString *）text 
 {
 [self dismissModalViewControllerAnimated：YES]; 
 _text.text = [NSString stringWithFormat：@％@，text]; 
} 
  

我的模态控制器

这包含一个包含委托的UITableView，当选择一个项目时，应该触发委托回调。

SuggestionViewController.h

  @protocol SelectTranslationDelegate< NSObject> 
  - （void）translationTextEntered：（NSString *）text; 
 @end 
 
 @interface SuggestionViewController：UIViewController< UITableViewDataSource，UITableViewDelegate，SelectTranslationDelegate> 
 {
 id< SelectTranslationDelegate>代表; 
} 
 
 @property（nonatomic，weak）id delegate; 
  

SuggestionViewController.h

  @synthesize delegate = _delegate; 
 
  - （void）tableView：（UITableView *）tableView didSelectRowAtIndexPath：（NSIndexPath *）indexPath 
 {
 ... 
 [delegate translationTextEntered：@f ]; 
 
} 
  

解决方案

是这样的：

MainViewController.h

  #importSuggestionViewController.h
 
 @interface MainViewController：UIViewController< SelectTranslationDelegate> 
 
 //  - （void）translationTextEntered：（NSString *）txt; <  - 不需要
  

声明 - （void）translationTextEntered :( NSString *）txt; 不需要，因为你说你符合 SelectTranslationDelegate 协议（ ; / > ）

MainViewController.m

  //您实例化的方法SuggestionViewController 
 {
 // ..做你的工作
 
 SuggestionViewController * suggestionViewController = [[SuggestionViewController alloc] init]; 
 
 suggestionViewController.delegate = self; //<  - 这是缺失的行
 
 [self presentModalViewController：suggestionViewController animated：YES]; 
 // [suggestionViewController release]; suggestionViewController = nil; //我假设你使用ARC 
 
} 
  

它也应该请注意，您的Modal视图控制器不应符合 SelectTranslationDelegate ，因为这很可能不是您的意图。所以你的声明应该是这样的：

  @interface SuggestionViewController：UIViewController< UITableViewDataSource，UITableViewDelegate> 
  

您想要回复的是 MainViewController 到 translationTextEntered： not SuggestionViewController 。 SuggestionViewController 是在委托中的消息调用 translationTextEntered： code>

I am trying to implement a delegate to enable a modal view to pass data back to a UIViewController.

I have two view controllers, my main UIViewController and the modal. Using the code below, the [delegate translationTextEntered:@"Test"]; doesn't affect the main screen (i.e. 'translationTextEntered' never gets called)

My Main Controller

This contains a method to be called when the modal has the user's value:

MainViewController.h

- (void)translationTextEntered:(NSString *)txt;

MainViewController.m

- (void)translationTextEntered:(NSString *)text
{
    [self dismissModalViewControllerAnimated:YES];
    _text.text = [NSString stringWithFormat:@"%@" , text];
}

My Modal Controller

This contains a UITableView which contains the delegate and, when an item is selected, should trigger the delegate callback.

SuggestionViewController.h

@protocol SelectTranslationDelegate <NSObject>
- (void)translationTextEntered:(NSString *)text;
@end

@interface SuggestionViewController : UIViewController <UITableViewDataSource, UITableViewDelegate, SelectTranslationDelegate>
{
    id<SelectTranslationDelegate> delegate;
}

@property (nonatomic, weak)id delegate;

SuggestionViewController.h

@synthesize delegate = _delegate;

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
     ...      
    [delegate translationTextEntered:@"f"];

}

解决方案

It should be something like this:

MainViewController.h

#import "SuggestionViewController.h"

@interface MainViewController : UIViewController <SelectTranslationDelegate>

// - (void)translationTextEntered:(NSString *)txt;  <- Not required

The declaration of - (void)translationTextEntered:(NSString *)txt; is not required because you say that you conform to the SelectTranslationDelegate protocol (The bit between the </>)

MainViewController.m

// The method where you instantiate SuggestionViewController
{
     // .. do your work

     SuggestionViewController *suggestionViewController = [[SuggestionViewController alloc] init];

     suggestionViewController.delegate = self; // <- This is the missing line

     [self presentModalViewController:suggestionViewController animated:YES];
     // [suggestionViewController release]; suggestionViewController = nil; // I'm assuming your using ARC

}

It should also be noted that your Modal view controller should not conform to SelectTranslationDelegate as this is most likely not your intention. So you declaration should be like:

@interface SuggestionViewController : UIViewController <UITableViewDataSource, UITableViewDelegate>

It is MainViewController that you want to respond to translationTextEntered: not SuggestionViewController. The SuggestionViewController is that one that makes the message call of translationTextEntered: on the delegate

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