Question

我很难绕过代表们。我尝试用一个简单的例子来教自己，但它只是没有用。

我的简单测试有两个类。 ClassA和ClassB。 ClassA具有委托定义。以及调用包含委托方法调用（-(void)buttonHasBeenPressed:(id)sender）的方法（-(void)buttonPressed）的按钮。设置了ClassB（我认为）来监听ClassA委托，当调用-(void)buttonHasBeenPressed:(id)sender时，它会写入控制台。

这是AppDelegate：

·H

#import <UIKit/UIKit.h>

@interface DelegateTestAppDelegate : NSObject <UIApplicationDelegate> {

}

@property (nonatomic, retain) IBOutlet UIWindow *window;

@end

的.m：

#import "DelegateTestAppDelegate.h"
#import "ClassA.h"

@implementation DelegateTestAppDelegate


@synthesize window=_window;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    ClassA *classA = [[ClassA alloc] init];
    [self.window addSubview:[classA view]];

    // Override point for customization after application launch.
    [self.window makeKeyAndVisible];
    return YES;
}


- (void)dealloc
{
    [_window release];
    [super dealloc];
}

@end

这是ClassA：

·H

#import <UIKit/UIKit.h>

@protocol ClassADelegate <NSObject>;
-(void)buttonPressed;
@end

@interface ClassA : UIViewController {

    id <ClassADelegate> delegate;
}

@property (retain) id <ClassADelegate> delegate;

-(void)buttonHasBeenPressed:(id)sender;

@end

的.m：

#import "ClassA.h"

@implementation ClassA

@synthesize delegate;

-(id)init {

    return self;
}

- (id)initWithNibName:(NSString *)nibNameOrNil
               bundle:(NSBundle *)nibBundleOrNil {
    return [self init];
}

-(void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [button addTarget:self action:@selector(buttonHasBeenPressed:) forControlEvents:UIControlEventTouchDown];
    [button setTitle:@"hola" forState:UIControlStateNormal];
    button.frame =CGRectMake(50, 200, 100, 20);
    [self.view addSubview:button];
}


-(void)buttonHasBeenPressed:(id)sender {
    [self.delegate buttonPressed];
    NSLog(@"button has been pressed");
}


@end

这是ClassB：

·H

#import <UIKit/UIKit.h>
#import "ClassA.h"


@interface ClassB : UIViewController <ClassADelegate> {

}

@end

的.m：

#import "ClassB.h"

@implementation ClassB

-(id)init {


    return self;
}

- (id)initWithNibName:(NSString *)nibNameOrNil
               bundle:(NSBundle *)nibBundleOrNil {
    return [self init];
}


-(void)buttonPressed {
    NSLog(@"delegating!");
}

@end

预期的结果是“按下按钮”和“委派！”单击“hola”按钮时写入控制台。

感谢您的帮助...... 肖恩

Answer 1

您的ClassB的实例在哪里？我在您发布的代码中找不到它。另外，在哪里将实例设置为ClassA作为其委托？我也找不到它。

如果你不做这两件事，你的代表将永远不会被调用。

Answer 2

您忘了将委托设置为符合 ClassADelegate 协议的类，此处应该是 ClassB 的对象

在iOS中需要帮助代表

2 个答案: