iOS开发，使用Category实现键盘弹出时，移动View以防被遮住

#import <UIKit/UIKit.h>

@interface UIView (AboutKeyboard)

@property (nonatomic) CGFloat moveDistince;
@property (nonatomic) UIView *moveView;

/*
 *指定一个View在键盘出现和消失时移动,如果存在superView则移动superView,否则移动自身
 */
- (void)registerWhenKeyboardShowAndHidden;
/*
 *指定一个View在键盘出现和消失时移动，并指定要移动的View
 */
- (void)registToMoveWhenKeyboardShowAndHideWithView:(UIView *)view;
/*
 *取消移动
 */
- (void)removeRegisterWhenKeyboardShowAndHidden;



@end

#import "UIView+AboutKeyboard.h"
#import <objc/runtime.h>

static const void *MoveDistince = &MoveDistince;
static const void *MoveView = &MoveView;

@implementation UIView (AboutKeyboard)

@dynamic moveDistince;
@dynamic moveView;

- (void)setMoveDistince:(CGFloat)moveDistince
{
    objc_setAssociatedObject(self, MoveDistince, @(moveDistince), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (CGFloat)moveDistince
{
    return [objc_getAssociatedObject(self, MoveDistince) floatValue];
}

- (void)setMoveView:(UIView *)moveView
{
    objc_setAssociatedObject(self, MoveView, moveView, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (UIView *)moveView
{
    return objc_getAssociatedObject(self, MoveView);
}

- (void)registerWhenKeyboardShowAndHidden
{
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillShow:)
                                                 name:UIKeyboardWillShowNotification
                                               object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillHidden:)
                                                 name:UIKeyboardWillHideNotification
                                               object:nil];
}

- (void)registToMoveWhenKeyboardShowAndHideWithView:(UIView *)view
{
    self.moveView = view;
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillShow:)
                                                 name:UIKeyboardWillShowNotification
                                               object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillHidden:)
                                                 name:UIKeyboardWillHideNotification
                                               object:nil];
}

- (void)keyboardWillShow:(NSNotification *)notification
{
    if (self.isFirstResponder)
    {
        if (!self.moveView)
        {
            if (self.superview)
                self.moveView = self.superview;//有superView
            else
                self.moveView = self;//没有superView的情况下移动自身
        }
        NSDictionary *userInfo = notification.userInfo;
        CGRect rect = [userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
        CGFloat duration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] floatValue];
        CGRect willMoveRect = self.moveView.frame;
        CGFloat selfY = CGRectGetMaxY(self.frame);
        CGFloat lastY = CGRectGetHeight(willMoveRect) - CGRectGetHeight(rect);
        if (duration > 0.0f)
        {
            if (selfY > lastY)
            {
                self.moveDistince = selfY - lastY;//需要移动的距离
                willMoveRect.origin.y -= self.moveDistince;
            }
        }
        else
        {
            CGFloat oldFloat = [userInfo[UIKeyboardFrameBeginUserInfoKey] CGRectValue].size.height;
            CGFloat move = (rect.size.height - oldFloat);
            willMoveRect.origin.y -= move;
            self.moveDistince += move;
        }
        [UIView animateWithDuration:duration animations:^{
            self.superview.frame = willMoveRect;
        }];
    }
}

- (void)keyboardWillHidden:(NSNotification *)notification
{
    if (self.isFirstResponder)
    {
        NSDictionary *userInfo = notification.userInfo;
        CGRect willMoveRect = self.moveView.frame;
        willMoveRect.origin.y += self.moveDistince;
        CGFloat duration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] floatValue];
        [UIView animateWithDuration:duration animations:^{
            self.superview.frame = willMoveRect;
        }];
    }
}

- (void)removeRegisterWhenKeyboardShowAndHidden
{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil];
}

@end