Question

我在创建协议时遇到问题，responsedsToSelector没有调用该方法。也许有人可以看到我出错的地方。

请参阅我的代码：

Protocol.h

#import <UIKit/UIKit.h>
@protocol CHTumblrMenuDelegate <NSObject>
@required
- (void)dismissView;
@end

typedef void (^CHTumblrMenuViewSelectedBlock)(void);

@interface CHTumblrMenuView : UIView<UIGestureRecognizerDelegate,CHTumblrMenuDelegate>{
    id<CHTumblrMenuDelegate>delegate;
}

@property (nonatomic, weak) id<CHTumblrMenuDelegate> delegate;

Protocol.m

- (id)initWithFrame:(CGRect)frame{
     self = [super initWithFrame:frame];
if (self) {
    // Initialization code
    UITapGestureRecognizer *ges = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(dismiss:)];
    ges.delegate = self;
    [self addGestureRecognizer:ges];
    self.backgroundColor = [UIColor clearColor];
    backgroundView_ = [[UIImageView alloc] initWithFrame:self.bounds];
    //backgroundView_.backgroundColor = TumblrBlue;
    backgroundView_.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;

    UIGraphicsBeginImageContext(backgroundView_.frame.size);
    [[UIImage imageNamed:@"background"] drawInRect:backgroundView_.bounds];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    backgroundView_.backgroundColor = [UIColor colorWithPatternImage:image];

    [self addSubview:backgroundView_];
    buttons_ = [[NSMutableArray alloc] initWithCapacity:6];


}
return self;
}

- (void)dismiss:(id)sender{
    NSLog(@"DIS");

    if (delegate == nil) {
       CHTumblrMenuView *vd = [[CHTumblrMenuView alloc]init];
       delegate = vd;
    }
    [delegate respondsToSelector:@selector(dismissView)];

    [self dropAnimation];
    double delayInSeconds = CHTumblrMenuViewAnimationTime  + CHTumblrMenuViewAnimationInterval * (buttons_.count + 1);
    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){

    [self removeFromSuperview];
});
}

ClassUseProtocol.m

CHTumblrMenuView *menuView = [[CHTumblrMenuView alloc] init];
menuView.delegate = self;

-(void)dismissView{
    NSLog(@"DismissView");
}

日志： 2016-06-06 22:44:07.258 ProtocolExample[7513:4030481] DIS

有没有人知道可能会发生什么？

Answer 1

你没有对respondsToSelector的结果做任何事情 - 这会返回一个布尔值，指示对象是否响应指定的选择器。如果它返回true，那么你应该调用委托方法： -

if ([delegate respondsToSelector:@selector(dismissView)]) {
    [delegate dismissView];
}

Answer 2

您的使用存在一些问题。正确使用是以下代码;

首先，self.delegate可以执行此方法，该方法由符合此协议CHTumblrMenuDelegate的其他类实现。
其次，必须由另一个类实现的dismissView方法。文件CHTumblrMenuView.h或CHTumblrMenuView.m要么实现协议CHTumblrMenuDelegate，要么实现必须实现的方法。
```
if ([self.delegate respondsToSelector:@selector(dismissView)]) {
       [self.delegate dismissView];
}
```
@interface CHTumblrMenuView：NSObject @end

@implementation CHTumblrMenuView - （无效）dismissView { 的NSLog（@ “dismissView”）; } @end

Answer 3

你已经双重定义了委托

@interface CHTumblrMenuView : UIView<UIGestureRecognizerDelegate,CHTumblrMenuDelegate>

@property（非原子，弱）id委托;

Answer 4

您的协议方法是@required，因此无需检查

 delegate respondsToSelector:@selector(dismissView)

如果是未定义的dismissView方法，则会出现编译时错误。您可以在行下面

 if (self.delegate && [self.delegate conformsToProtocol:@protocol(CHTumblrMenuDelegate)]) {
    [self.delegate dismissView];
 }

在这种情况下，协议确实responseToSelector对我不起作用吗？

4 个答案: