iOS-虛擬鍵盤遮蓋問題

問題：避免虛擬鍵盤遮蓋，主要是經過view上移下移解決，因此本身封裝工具類KeyboardUtils；代碼以下；

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface KeyboardUtils : NSObject

- (instancetype)initWithTargetView:(UIView *)view;
- (void)updateViewWithRect:(CGRect)rect;

@end


#import "KeyboardUtils.h"

@interface KeyboardUtils ()

@property (nonatomic, strong) UIView *view;
@property (nonatomic, assign) CGRect rect;
@property (nonatomic, strong) NSDictionary *userInfo;

@end

CGFloat const defaultBottomOffset = 80.0f;

@implementation KeyboardUtils

- (instancetype)initWithTargetView:(UIView *)view {
    
    self = [super init];
    if (self) {
        
        self.view = view;
        for (NSString *name in @[UIKeyboardWillShowNotification,UIKeyboardWillHideNotification]) {
            [[NSNotificationCenter defaultCenter] addObserver:self
                                                     selector:@selector(receiveNotification:)
                                                         name:name object:nil];
        }
    }
    
    return self;
}

- (void)updateViewWithRect:(CGRect)rect {
    
    self.rect = rect;
    if (_userInfo) {
        [self avoidCoverKeyboardWithuserInfo:_userInfo frame:_rect];
    }
}

- (void)receiveNotification:(NSNotification *)notification {
    
    NSDictionary *userInfo = notification.userInfo;
    CGFloat duration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] floatValue];
    
    if ([notification.name isEqualToString:UIKeyboardWillShowNotification]) {
        
        self.userInfo = notification.userInfo;
        [self avoidCoverKeyboardWithuserInfo:_userInfo frame:_rect];
        
    } else if ([notification.name isEqualToString:UIKeyboardWillHideNotification]) {
        
        self.userInfo = nil;
        [self moveDown:duration];
    }
}

- (void)avoidCoverKeyboardWithuserInfo:(NSDictionary *)userInfo frame:(CGRect)frame {
    
    CGFloat duration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] floatValue];
    CGRect rect = [userInfo[UIKeyboardFrameBeginUserInfoKey] CGRectValue];
    CGFloat offset = (CGRectGetMaxY(frame) + defaultBottomOffset) - (SCREEN_HEIGHT - rect.size.height);
    
    if (offset > 0) {
        
        [self moveUp:duration offset:offset];
        
    } else {
        
        [self moveDown:duration];
    }
}

- (void)moveUp:(NSTimeInterval)duration offset:(CGFloat)offset {
    
    [UIView animateWithDuration:duration animations:^{
        
        _view.frame = CGRectMake(0, -offset, SCREEN_WIDTH, SCREEN_HEIGHT);
    }];
}
- (void)moveDown:(NSTimeInterval)duration {
    
    [UIView animateWithDuration:duration animations:^{
        
        _view.frame = CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
    }];
}

- (void)dealloc {
    
    self.userInfo = nil;
    for (NSString *name in @[UIKeyboardWillShowNotification,UIKeyboardWillHideNotification]) {
        [[NSNotificationCenter defaultCenter] removeObserver:self
                                                        name:name
                                                      object:nil];
    }
}
@end

解釋：- (void)updateViewWithRect:(CGRect)rect;方法實時的計算view需上移的距離，而後執行動畫。