iOS捕捉键盘移动（根据键盘移动view跟随上下）

一时失言乱红尘 2023-10-17 05:21 10阅读 0赞

在QQ上我们经常会看到进入聊天页面时，输入框会跟着键盘的弹起而上下移动，本demo就是仿照此功能而设计

代码如下：

#pragma mark- vc
    - (void)viewDidLoad {
        [super viewDidLoad];
        self.title = @"与xxx聊天中";
        
            //从IOS7开始，导航条和状态栏合为一体，而且呈半透明状，viewController.view的坐标0，0点在屏幕左上方，如果子视图位置在view的顶部，就会被导航条遮盖，所以，viewController会对自身的第一个子视图(scrollView)顶部添加64像素的contentInset，避免scrollView内容被查盖。
        self.automaticallyAdjustsScrollViewInsets = NO;
        
        _table.contentInset = UIEdgeInsetsMake(64, 0, 0, 0);
        _table.delegate = self;
        _table.dataSource = self;
        
            //设置分割线的样式。
        _table.separatorStyle = UITableViewCellSeparatorStyleNone;
        
            //scrollView滑动时键盘消失；
            //_table.keyboardDismissMode = UIScrollViewKeyboardDismissModeOnDrag;
        
        [self loadSubView];
        
            //监听键盘frame变化的通知，键盘位置发生变化时，让输入框位置也随之变化。
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(receiveKeyboardFrameChangeNotification:) name:UIKeyboardWillChangeFrameNotification object:nil];
        
        _array = [[NSMutableArray alloc] initWithCapacity:0];
        
        [_table registerNib:[UINib nibWithNibName:@"SelfCell" bundle:nil] forCellReuseIdentifier:@"self"];
        
        [_table registerNib:[UINib nibWithNibName:@"OtherCell" bundle:nil] forCellReuseIdentifier:@"other"];
    }
    
    - (void)loadSubView{
        _inputView = [[UIView alloc] initWithFrame:CGRectMake(0, 627, 375, 40)];
        [self.view addSubview:_inputView];
        
        UIImageView *imgView = [[UIImageView alloc] initWithFrame:_inputView.bounds];
        imgView.image = [UIImage imageNamed:@"chatinputbg.png"];
        [_inputView addSubview:imgView];
        [imgView release];
        
        _textField = [[UITextField alloc] initWithFrame:CGRectMake(3, 3, 369, 34)];
        _textField.borderStyle = UITextBorderStyleRoundedRect;
            //设置return键的样式
        _textField.returnKeyType = UIReturnKeySend;
            //自动可用return键。
        _textField.enablesReturnKeyAutomatically = YES;
            //英文首字母是否大写。
        _textField.autocapitalizationType = UITextAutocapitalizationTypeNone;
            //清除键的显示方式。
        _textField.clearButtonMode = UITextFieldViewModeWhileEditing;
        [_inputView addSubview:_textField];
        
        _textField.delegate = self;
    }
    
    #pragma mark- notificationMethod
    - (void)receiveKeyboardFrameChangeNotification:(NSNotification *)noti{
            //NSLog(@"%@",noti.userInfo);
        
            //NSValue值类,基本类型和结构体不能直接放入数组和字典中，如果需要把结构体放入数组或字典，那么必须把结构体转换为NSValue，然后把NSValue放入字典或数组。
        NSValue *value = [noti.userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
        
            //CGRect rect = [value CGRectValue];
        CGRect rect;
        [value getValue:&rect];
        
        
        [UIView beginAnimations:nil context:nil];
        [UIView setAnimationDuration:[[noti.userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey] floatValue]];
            //7是键盘动画专用速率
        [UIView setAnimationCurve:[[noti.userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] integerValue]];
        _inputView.frame = CGRectMake(0, rect.origin.y-40, 375, 40);
        _table.frame = CGRectMake(0, 0, 375, _inputView.frame.origin.y);
        if (_array.count>1) {
            [_table scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:_array.count-1 inSection:0] atScrollPosition:UITableViewScrollPositionNone animated:NO];
        }
        [UIView commitAnimations];
    }
    
    #pragma mark- scrollViewDelegate
        //scrollView将要开始拖拽时的回调方法。
    - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
        [self.view endEditing:YES];
    }
    
    #pragma mark- textField
        //return键点击时调用。
    - (BOOL)textFieldShouldReturn:(UITextField *)textField{
        
        [_array addObject:textField.text];
        textField.text = @"";
        [_table reloadData];
        
            //scrollToRowAtIndexPath让tableView滚动到某一行，atScrollPosition参数是让这一行滚动出来之后显示在tableView上的位置（如果有可能）
        [_table scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:_array.count-1 inSection:0] atScrollPosition:UITableViewScrollPositionNone animated:YES];
        return YES;
    }
    
    #pragma mark- table
    - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
        return _array.count;
    }
    
    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
        
        NSString *text = [_array objectAtIndex:indexPath.row];
            //boundingRectWithSize计算出文本显示的边框大小。第一个参数是限定的宽度和高度。第二个参数是计算选项，第三个参数是计算的文本的具体属性。
        NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc] init];
        style.lineBreakMode = NSLineBreakByCharWrapping;
        CGRect rect = [text boundingRectWithSize:CGSizeMake(220, 0) options:NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:17],NSParagraphStyleAttributeName:style} context:nil];
        [style release];
        
        if (indexPath.row%2 == 0) {
            SelfCell *cell = [tableView dequeueReusableCellWithIdentifier:@"self"];
            cell.messageLabel.frame = CGRectMake(30, 10, rect.size.width, rect.size.height);
            cell.bubbleImageView.frame = CGRectMake(20, 5, rect.size.width+20, rect.size.height+10);
            cell.messageLabel.text = text;
            return cell;
        }else{
            OtherCell *cell = [tableView dequeueReusableCellWithIdentifier:@"other"];
            cell.messageLabel.frame = CGRectMake(375-rect.size.width-30, 10, rect.size.width, rect.size.height);
            cell.bubbleImageView.frame = CGRectMake(375-rect.size.width-40, 5, rect.size.width+20, rect.size.height+10);
            cell.messageLabel.text = text;
            return cell;
        }
    }
    
    - (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
        NSString *text = [_array objectAtIndex:indexPath.row];
        CGRect rect = [text boundingRectWithSize:CGSizeMake(220, 0) options:NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:17]} context:nil];
        return rect.size.height+20;
    }

cell中

- (void)awakeFromNib {
        // Initialization code
        UIImage *img = [UIImage imageNamed:@"bubble.png"];
            //stretchableImageWithLeftCapWidth设置边帽，能够使图片在拉伸或压缩时只按照某个像素点的颜色进行填充。（保证图片拉伸时不变形）
        self.bubbleImageView.image = [img stretchableImageWithLeftCapWidth:25 topCapHeight:20];
        
        self.messageLabel.numberOfLines = 0;
            //折行方式
        self.messageLabel.lineBreakMode = NSLineBreakByCharWrapping;
    }

效果如下：  
![Center][]

[Center]: https://img-blog.csdn.net/20160629203122992?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center