另一种思路监听键盘的隐藏与显示

2016-03-21

监听键盘的隐藏与显示

监听键盘的隐藏与显示，其实原始的比较简单，只需要观察四个通知名称：

`UIKeyboardWillShowNotification` 
`UIKeyboardWillHideNotification`
`UIKeyboardDidShowNotification`
`UIKeyboardDidHideNotification`

实现方式是这样的 

`[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];`

`[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector    (keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];`
`[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];`

`[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector    (keyboardDidHide:) name:UIKeyboardDidHideNotification object:nil];`

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-(void)keyboardWillHide:(NSNotification*)aNotification{
 //代码
}

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-(void)keyboardWillShow:(NSNotification*)aNotification{
	//代码
}

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-(void)keyboardDidHide:(NSNotification*)aNotification{
 //代码
}

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-(void)keyboardDidShow:(NSNotification*)aNotification{
	//代码
}

但是，在我的项目里面，如果使用以上方法去监听键盘的隐藏与显示，会编写比较多的代码以及代码逻辑判断很复杂，还有就是，在系统键盘与第三方键盘之间切换时，有时候不会走这个方法，因此，我就换了一种思路去解决这样的bugs，我仅仅是通过监听UIKeyboardWillChangeFrameNotification这个通知，然后通过键盘的y坐标与屏幕高度作比较，如果y值 大于或者等于屏幕高度则为键盘隐藏，相反，y值小于屏幕高度则为键盘显示。这样既可以解决第三方键盘 的高度变化的问题，又可以少写代码。没有代码展示都是耍流氓！
代码如下：
.h中

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typedef void(^GRUCAnimationsWithKeyboardBlock)(CGRect keyboardRect,CGFloat 	keyboardOffset,NSTimeInterval duration,BOOL isShowing);
typedef void(^GRUCBeforeAnimationsWithKeyboardBlock)(CGRect keyboardRect,CGFloat 	keyboardOffset,NSTimeInterval duration,BOOL isShowing);
typedef void(^GRUCCompletionKeyboardAnimationsBlock)(BOOL finished);
typedef void(^GRUCCompletionBeforeUnsubscribeKeyboardBlcok)(void);


@interface GRUCChatPanelView (KeyboardAnimation)
@property (nonatomic,assign) CGFloat yOffset; // keyboard offset if yOfset < 0, the keyboard is Showing,otherwise, it is Hiddening.

/**
 *  To the notification center, subscribe to a change in the keyboard position of the observer.
	 *  The name of the object observered is 'UIKeyboardWillChangeFrameNotification'.
 *  @param animations perform the  same as the keyboard animations.
	 *  @param completion after the keyboard animations completion, Maybe you have other things to do.
	*/

- (void)gruc_subscribeKeyboardWithAnimations:(GRUCAnimationsWithKeyboardBlock)animations completion:(GRUCCompletionKeyboardAnimationsBlock)completion;
- (void)gruc_subscribeUIkeyboardNotification;

/**
 *  To the notification center,subscribe to a change in the keyboard postion ofhte observer.
	 *
 *  @param beforeAnimations before performing the keyboard animations,Maybe you 	have other things to do.
	 *  @param animations       perform the keyboard animations.
  	 *  @param completion       the keyboard animaitons completion.
	*/

- (void)gruc_subscribeKeyboardWithBeforeAnimations:(GRUCBeforeAnimationsWithKeyboardBlock)beforeAnimations
                                       animations:(GRUCAnimationsWithKeyboardBlock)animations
                                       completion:(GRUCCompletionKeyboardAnimationsBlock)completion;


/**
	*  Cancel subscriber for change the postion of the keyboard.
	*/
- (void)gruc_unsubscribeKeyboard;
- (void)gruc_unsubscribeUIKeyboardNotification;

/**
	*  Cancel subcriber for change the postion of the keyboard. but before canceling subcriber,Maybe you have other things to do.
*
	*  @param completion completion context.
   */

- (void)gruc_beforeUnsubscribeKeyboard:(GRUCCompletionBeforeUnsubscribeKeyboardBlcok)completion;

.m中

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	-(void)gruc_subscribeKeyboardWithAnimations:(GRUCAnimationsWithKeyboardBlock)animations completion:(GRUCCompletionKeyboardAnimationsBlock)completion{
    [self gruc_subscribeKeyboardWithBeforeAnimations:nil animations:animations completion:completion];
	}
 	-(void)gruc_subscribeKeyboardWithBeforeAnimations:(GRUCBeforeAnimationsWithKeyboardBlock)beforeAnimations animations:(GRUCAnimationsWithKeyboardBlock)animations completion:(GRUCCompletionKeyboardAnimationsBlock)completion{
    [self gruc_unsubscribeKeyboard];
    objc_setAssociatedObject(self, GRUCBeforeAnimationsBlockAssociationKey, beforeAnimations, OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, GRUCAnimationsBlockAssociationKey, animations, OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, GRUCAnimationsCompletionBlockAssociationKey, completion, OBJC_ASSOCIATION_COPY_NONATOMIC);
    [self gruc_subscribeUIkeyboardNotification];
	}
 	-(void)gruc_subscribeUIkeyboardNotification{
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(gruc_keyboardWillChangeFrame:) name:UIKeyboardWillChangeFrameNotification object:nil];
	}
	-(void)gruc_unsubscribeKeyboard{
    [self gruc_beforeUnsubscribeKeyboard:nil];
	}
 	-(void)gruc_unsubscribeUIKeyboardNotification{
    [[NSNotificationCenter defaultCenter]removeObserver:self name:UIKeyboardWillChangeFrameNotification object:nil];
	}
 	-(void)gruc_beforeUnsubscribeKeyboard:(GRUCCompletionBeforeUnsubscribeKeyboardBlcok)completion{
    if (completion) {
        completion();
    }
    objc_setAssociatedObject(self, GRUCBeforeAnimationsBlockAssociationKey, nil, OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, GRUCAnimationsBlockAssociationKey, nil, OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, GRUCAnimationsCompletionBlockAssociationKey, nil, OBJC_ASSOCIATION_COPY_NONATOMIC);
    [self gruc_unsubscribeUIKeyboardNotification];
	}

#pragma mark -
#pragma mark -- private methods

-(void)gruc_keyboardWillChangeFrame:(NSNotification *)notification{
    
    BOOL isShowing;
    NSDictionary *info = [notification userInfo];
    CGFloat duration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] floatValue];
    CGRect beginKeyboardRect = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue];
    CGRect endKeyboardRect = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
  
    UIViewAnimationCurve curve = (UIViewAnimationCurve)[[notification.userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] integerValue];
    CGFloat offset = endKeyboardRect.origin.y - beginKeyboardRect.origin.y;
    self.yOffset += offset;
    
    isShowing = endKeyboardRect.origin.y >= kScreenHeight ?NO:YES;
    
    GRUCAnimationsWithKeyboardBlock animationsBlock = objc_getAssociatedObject(self, GRUCAnimationsBlockAssociationKey);
    GRUCBeforeAnimationsWithKeyboardBlock beforeAnimationsBlock = objc_getAssociatedObject(self, GRUCBeforeAnimationsBlockAssociationKey);
    GRUCCompletionKeyboardAnimationsBlock completionBlock = objc_getAssociatedObject(self, GRUCAnimationsCompletionBlockAssociationKey);
    
    if (beforeAnimationsBlock) {
        beforeAnimationsBlock(endKeyboardRect,offset,duration,isShowing);
    }
    
    [UIView animateWithDuration:duration delay:0 options:UIViewAnimationOptionBeginFromCurrentState animations:^{
        [UIView setAnimationCurve:curve];
        if (animationsBlock) {
            animationsBlock(endKeyboardRect,offset,duration,isShowing);
        }
    } completion:completionBlock];
    
	}
	-(CGFloat)yOffset{
    return [objc_getAssociatedObject(self, externVarableKey) doubleValue];
	}
	-(void)setYOffset:(CGFloat)yOffset{
    objc_setAssociatedObject(self, externVarableKey, @(yOffset), OBJC_ASSOCIATION_COPY_NONATOMIC);
	}

总结

如有发现bugs，请联系`woodjobber@outlook.com`

项目地址：https://github.com/woodjobber/GRUCChatPanelView

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