实现模式视图控制器数据传输的委托方法 [英] Implementing delegate methods for modal view controller data transfer

问题描述

我有一个简单的项目来呈现一个模态视图控制器，并根据按下的模态VC中的哪个按钮传回一个字符串。我基于这一切都是在iTunes U上看斯坦福课程。看起来我有一切正确，但是我得到了一些编译器警告。

首先我得到一个从 TransferViewController.m


中的不兼容指针类型传递'setDelegate：

第二个我收到四个警告称为无效的接收者类型'id< MyModalViewControllerDelegate> *'但这些不会显示在构建结果区域在 MyModalViewController.m 中的违规行旁边，每个按钮操作中的两行。

这是代码...

  // TransferViewController.h 
 
 #import< UIKit / UIKit.h> 
 #importMyModalViewController.h; 
 
 @interface TransferViewController：UIViewController< MyModalViewControllerDelegate> {
 UILabel * label; 
 UIButton *按钮; 
} 
 
 @property（nonatomic，retain）IBOutlet UILabel * label; 
 @property（nonatomic，retain）UIButton *按钮; 
 
  - （IBAction）updateText; 
 
 @end 
  

---

  // TransferViewController.m 
 
 #importTransferViewController.h
 
 @implementation TransferViewController 
 
 @synthesize标签; 
 @synthesize按钮; 
 
  - （IBAction）updateText {
 MyModalViewController * myModalViewController = [[MyModalViewController alloc] init]; 
 myModalViewController.delegate = self; //我在这里得到警告。 
 [self presentModalViewController：myModalViewController animated：YES]; 
 [myModalViewController release]; 
} 
 
  - （void）myModalViewController :( MyModalViewController *）controller didFinishSelecting：（NSString *）selectedDog {
 label.text = selectedDog; 
 [self dismissModalViewControllerAnimated：YES]; 
} 
 
 @end 
  

---

  // MyModalViewController.h 
 
 #import< UIKit / UIKit.h> 
 
 @protocol MyModalViewControllerDelegate; 
 
 @interface MyModalViewController：UIViewController {
 UIButton * abby; 
 UIButton * zion; 
 id< MyModalViewControllerDelegate>代表; 
} 
 
 @property（assign）id< MyModalViewControllerDelegate>代表; 
 
  - （IBAction）selectedAbby; 
  - （IBAction）selectedZion; 
 
 @end 
 
 @protocol MyModalViewControllerDelegate< NSObject> 
 
 @optional 
 
  - （void）myModalViewController：（MyModalViewController *）controller didFinishSelecting：（NSString *）selectedDog; 
 
 @end 
  

---

  // MyModalViewController.m 
 
 #importMyModalViewController.h
 
 @implementation MyModalViewController 
 
 @synthesize代表; 
 
  - （IBAction）selectedAbby {
 if（[self.delegate responsesToSelector：@selector（myModalViewController：didFinishSelecting :)]）{
 [self.delegate myModalViewController：self didFinishSelecting： @Abby]; 
} 
} 
 
  - （IBAction）selectedZion {
 if（[self.delegate responsesToSelector：@selector（myModalViewController：didFinishSelecting :)]）{
 [self.delegate myModalViewController：self didFinishSelecting：@Zion]; 
} 
 
} 
  

解决方案

在 id< something> 之前和委托之前，删除 * 。

所以使这个

  id< MyModalViewControllerDelegate> *代表; 
  

这个

  id< MyModalViewControllerDelegate>代表; 
  

I have a simple project to present a modal view controller and transfer back a string based on which button in the modal VC that gets pressed. I based it all on watching the Stanford class on iTunes U. It looks like I have everything correct, but I get a couple of compiler warnings.

First I get one called passing argument 1 of 'setDelegate:' from incompatible pointer type in TransferViewController.m

Second I get four warnings called Invalid receiver type 'id <MyModalViewControllerDelegate>*' but these aren't displayed in the build results area, rather next to the offending lines in MyModalViewController.m, both lines in each of the button actions.

Here's the code...

//  TransferViewController.h

#import <UIKit/UIKit.h>
#import "MyModalViewController.h";

@interface TransferViewController : UIViewController <MyModalViewControllerDelegate> {
    UILabel *label;
    UIButton *button;
}

@property (nonatomic, retain) IBOutlet UILabel *label;
@property (nonatomic, retain) UIButton *button;

- (IBAction)updateText;

@end

---

//  TransferViewController.m

#import "TransferViewController.h"

@implementation TransferViewController

@synthesize label;
@synthesize button;

- (IBAction)updateText {
    MyModalViewController *myModalViewController = [[MyModalViewController alloc] init];
    myModalViewController.delegate = self; // I get the warning here.
    [self presentModalViewController:myModalViewController animated:YES];
    [myModalViewController release];
}

- (void)myModalViewController:(MyModalViewController *)controller didFinishSelecting:(NSString *)selectedDog {
    label.text = selectedDog;
    [self dismissModalViewControllerAnimated:YES];
}

@end

---

//  MyModalViewController.h

#import <UIKit/UIKit.h>

@protocol MyModalViewControllerDelegate;

@interface MyModalViewController : UIViewController {
    UIButton *abby;
    UIButton *zion;
    id <MyModalViewControllerDelegate> delegate;
}

@property (assign) id <MyModalViewControllerDelegate> delegate;

- (IBAction)selectedAbby;
- (IBAction)selectedZion;

@end

@protocol MyModalViewControllerDelegate <NSObject>

@optional

- (void)myModalViewController:(MyModalViewController *)controller didFinishSelecting:(NSString *)selectedDog;

@end

---

//  MyModalViewController.m

#import "MyModalViewController.h"

@implementation MyModalViewController

@synthesize delegate;

- (IBAction)selectedAbby {
    if ([self.delegate respondsToSelector:@selector (myModalViewController:didFinishSelecting:)]) {
        [self.delegate myModalViewController:self didFinishSelecting:@"Abby"];
    }
}

- (IBAction)selectedZion {
    if ([self.delegate respondsToSelector:@selector (myModalViewController:didFinishSelecting:)]) {
        [self.delegate myModalViewController:self didFinishSelecting:@"Zion"];
    }

}

解决方案

Get rid of those *s after id <something> and before delegate.

So make this

id <MyModalViewControllerDelegate> *delegate;

this

id <MyModalViewControllerDelegate> delegate;

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