iOS协议和代理人的例子 [英] iOS- protocols and delegates on the example

问题描述

好吧，我正在搜索，但没有任何方法为我工作。以下代码基于许多教程和Apple文档，但我无法让它工作。有人可以帮忙吗？

代码正在崩溃：obj.delegatee = self; （在类Bh中），还有方法respondToSelector和performSelector：withObject不被识别。

我想设置委托对象，当我们点击特定图片。

类啊：

  @interface AViewController ：UIViewController< UIScrollViewDelegate> {
 id delegatee; 
} 
 @property（nonatomic，assign）id< AViewControllerDelegate>代表团
 @end 
 
 @protocol AViewControllerDelegate 
 @optional 
  - （void）tappedImage：（int） 
 @end 
  

class Am：

  @dynamic delegatee; 
  - （void）handleSingleTap：（UIGestureRecognizer *）gestureRecognizer {
 UIImageView * imageView =（UIImageView *）[gestureRecognizer视图]; 
 int a = imageView.tag; 
 
 if（[self.delegatee respondToSelector：@selector（tappedImage :)]）
 [self.delegatee performSelector：@selector（tappedImage :) withObject：[NSNumber numberWithInt：a]]; 
  

}

class Bh：

  #importAViewController.h
 @interface BViewController：UIViewController< AViewControllerDelegate> {...} 
  

class Bm：

   - （void）viewDidLoad 
 {
 [super viewDidLoad]; 
 // ...一些代码
 
 AViewController * obj = [[AViewController alloc] init] autorelease]; 
 obj.delegatee = self; 
} 
 
  - （void）tappedImage：（int）tag {
 UIImageView * imgView = [[UIImageView alloc] initWithImage：[UIImage imageNamed：[NSString stringWithFormat：@％ d.png，tag]]]; 
 CViewController * NView = [[CViewController alloc] initWithPicture：imgView.image]; 
 [self presentModalViewController：NView animated：YES]; 
 [NView release]; NView = nil; 
} 
  

非常感谢任何帮助，我希望它能帮助我了解协议

解决方案

两件事。

1. （你的崩溃）你宣称你的委托人/ / c $ c>为@dynamic而不是@synthesized，这意味着你负责创建 - （void ）setDelegatee：（id< AViewControllerDelegate>）（和getter）方法。修复：只需将它从 @dynamic 更改为 @synthesize delegatee;




2. （您的警告）每当您想要调用协议中未明确定义的方法时，您的协议将需要符合另一个协议:)。修复：将 NSObject 协议添加到您的decleration。

@protocol AViewControllerDelegate< NSObject>

Ok, i was searching but there wasn't any method that was working for me. Following code bases on many tutorials and Apple documentation, but i can't get it to work. Can anybody help please?

Code is crashing at: obj.delegatee = self; (in class B.h), also methods respondsToSelector and performSelector:withObject aren't recogized.

I want to set delegate object, on which there will be a method called when we tap on particular picture.

class A.h:

@interface AViewController : UIViewController <UIScrollViewDelegate>{
    id delegatee;
}
@property (nonatomic, assign) id <AViewControllerDelegate> delegatee;
@end

@protocol AViewControllerDelegate
@optional
- (void) tappedImage:(int)tag;
@end

class A.m:

@dynamic delegatee;
- (void)handleSingleTap:(UIGestureRecognizer *)gestureRecognizer {
UIImageView *imageView = (UIImageView *)[gestureRecognizer view];
int a = imageView.tag;

if ([self.delegatee respondsToSelector:@selector(tappedImage:)])
    [self.delegatee performSelector:@selector(tappedImage:) withObject: [NSNumber numberWithInt:a]];

}

class B.h:

#import "AViewController.h"
@interface BViewController : UIViewController <AViewControllerDelegate> {...}

class B.m:

- (void)viewDidLoad
{
[super viewDidLoad];
//... some code

AViewController *obj = [[[AViewController alloc] init] autorelease];
obj.delegatee = self;
}

- (void) tappedImage:(int)tag{
UIImageView *imgView = [[UIImageView alloc] initWithImage:[UIImage imageNamed: [NSString stringWithFormat: @"%d.png",tag]]];
CViewController *NView = [[CViewController alloc] initWithPicture: imgView.image];
[self presentModalViewController:NView animated:YES];
[NView release]; NView = nil;
}

Many thanks for any help, i hope it will help me to understand how protocols work.

解决方案

Two things.

1. (Your Crash) You declared your delegatee as @dynamic instead of @synthesized which means you are responsible for creating the -(void)setDelegatee:(id<AViewControllerDelegate>) (and the getter) method. Fix: Simply change it from @dynamic to @synthesize delegatee;

2. (Your warnings) Whenever you want to call methods that you do not explicitly define in your protocol, then your protocol will need to conform to another protocol :). Fix: Add the NSObject protocol to your decleration.

@protocol AViewControllerDelegate<NSObject>

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