前言

一款聊天类型的APP，文字输入框是必不可少的，在此简单写了一个Demo供大家参考，希望能够抛砖引玉。

思路

为了方便封装UI，将UITextView封装到一个UIView中。UIView内部需要监听键盘的弹出和消失，根据文字动态计算UITextView的高度，达到指定的最高高度后，UITextView高度不变化，文字自动上移。

1.基本UI框架搭建

UI比较简单，就不细说了，具体代码如下。

-(void)initView {
    self.backgroundColor = [UIColor whiteColor];
    //顶部线条
    self.topLine = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.CLwidth, 1)];
    self.topLine.backgroundColor = RGBACOLOR(0, 0, 0, 0.2);
    [self addSubview:self.topLine];
    //底部线条
    self.bottomLine = [[UIView alloc] initWithFrame:CGRectMake(0, self.CLheight - 1, self.CLwidth, 1)];
    self.bottomLine.backgroundColor = RGBACOLOR(0, 0, 0, 0.2);
    [self addSubview:self.bottomLine];
    //边框
    self.edgeLineView = [[UIView alloc]init];
    self.edgeLineView.CLwidth = self.CLwidth - 50 - 30;
    self.edgeLineView.CLleft = 10;
    self.edgeLineView.layer.cornerRadius = 5;
    self.edgeLineView.layer.borderColor = RGBACOLOR(0, 0, 0, 0.5).CGColor;
    self.edgeLineView.layer.borderWidth = 1;
    self.edgeLineView.layer.masksToBounds = YES;
    [self addSubview:self.edgeLineView];
    //输入框
    self.textView = [[UITextView alloc] init];;
    self.textView.CLwidth = self.CLwidth - 50 - 46;
    self.textView.CLleft = 18;
    self.textView.enablesReturnKeyAutomatically = YES;
    self.textView.delegate = self;
    //关闭连续布局
    self.textView.layoutManager.allowsNonContiguousLayout = NO;
    self.textView.scrollsToTop = NO;
    //去掉自带的间距
    self.textView.textContainerInset = UIEdgeInsetsZero;
    self.textView.textContainer.lineFragmentPadding = 0;
    [self addSubview:self.textView];
    //占位文字
    self.placeholderLabel = [[UILabel alloc] init];
    self.placeholderLabel.CLwidth = self.textView.CLwidth - 10;
    self.placeholderLabel.textColor = RGBACOLOR(0, 0, 0, 0.5);
    self.placeholderLabel.CLleft = 23;
    [self addSubview:self.placeholderLabel];
    //发送按钮
    self.sendButton = [[UIButton alloc] initWithFrame:CGRectMake(self.CLwidth - 50 - 10, self.CLheight - 30 - 10, 50, 30)];
    [self.sendButton.layer setBorderWidth:1.0];
    [self.sendButton.layer setCornerRadius:5.0];
    self.sendButton.layer.borderColor = RGBACOLOR(0, 0, 0, 0.5).CGColor;
    self.sendButton.enabled = NO;
    self.sendButton.titleLabel.font = [UIFont systemFontOfSize:16];
    [self.sendButton setTitle:@"发送" forState:UIControlStateNormal];
    [self.sendButton setTitleColor:RGBACOLOR(0, 0, 0, 0.2) forState:UIControlStateNormal];
    [self.sendButton addTarget:self action:@selector(didClicksendButton) forControlEvents:UIControlEventTouchUpInside];
    [self addSubview:self.sendButton];
    self.fontSize = 20;
    self.textViewMaxLine = 3;
}

2.监听键盘弹出和收回

输入框需要跟随键盘的弹出和收回，监听键盘相对应的通知事件，根据键盘弹出时间等做出相应的处理。

#pragma mark keyboardnotification
- (void)keyboardWillShow:(NSNotification *)notification {
    CGRect keyboardFrame = [notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
    _keyboardHeight = keyboardFrame.size.height;
    CGFloat duration = [notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    [UIView animateWithDuration:duration animations:^{
        self.CLy = keyboardFrame.origin.y - self.CLheight;
    }];
}
- (void)keyboardWillHidden:(NSNotification *)notification {
    CGFloat duration = [notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    [UIView animateWithDuration:duration animations:^{
        self.CLy = CLscreenHeight;
    }];
}

3.根据文字动态改变输入框高度

在UITextView代理中，通过文字计算需要的高度，判断是否达到最大高度，没有达到的情况就改变输入框的高度，超过最大高度，文字上移，高度不变。

#pragma mark UITextViewDelegate
- (void)textViewDidChange:(UITextView *)textView {
    self.placeholderLabel.hidden = textView.text.length;
    if (textView.text.length == 0) {
        self.sendButton.enabled = NO;
        [self.sendButton setTitleColor:RGBACOLOR(0, 0, 0, 0.2) forState:UIControlStateNormal];
    }else{
        self.sendButton.enabled = YES;
        [self.sendButton setTitleColor:RGBACOLOR(0, 0, 0, 1.0) forState:UIControlStateNormal];
    }
    CGFloat contentSizeH = textView.contentSize.height;
    CGFloat lineH = textView.font.lineHeight;
    CGFloat maxTextViewHeight = ceil(lineH * self.textViewMaxLine + textView.textContainerInset.top + textView.textContainerInset.bottom);
    if (contentSizeH <= maxTextViewHeight) {
        textView.CLheight = contentSizeH;
    }else{
        textView.CLheight = maxTextViewHeight;
    }
    self.CLheight = ceil(textView.CLheight) + 10 + 10;
    self.CLbottom = CLscreenHeight - _keyboardHeight;
    [textView scrollRangeToVisible:NSMakeRange(textView.selectedRange.location, 1)];
}

接口

简单封装了一下，给出了一些接口，具体如下。

/**设置输入框最大行数*/
@property (nonatomic, assign) NSInteger textViewMaxLine;
/**输入框文字大小*/
@property (nonatomic, assign) CGFloat fontSize;
/**占位文字*/
@property (nonatomic, copy) NSString *placeholder;

/**收回键盘*/
-(void)bounceToolbar;
/**弹出键盘*/
- (void)popToolbar;
/**点击发送后的文字*/
- (void)inputToolbarSendText:(inputTextBlock)sendText;

效果图

其他

1.修改光标宽高

自定义一个继承自UITextView的控件，内部重写下面方法即可。

- (CGRect)caretRectForPosition:(UITextPosition *)position
{
    CGRect originalRect = [super caretRectForPosition:position];
    
    originalRect.size.width = 2;
    originalRect.size.height = self.font.lineHeight;

    return originalRect;
}

2.修改光标颜色

[self.textView setTintColor:[UIColor redColor]];

3.修改行间距

NSMutableParagraphStyle *paragraphStyle = [NSMutableParagraphStyle new];
paragraphStyle.lineSpacing = 20;// 字体的行间距    
NSDictionary *attributes = @{
                                 NSFontAttributeName:[UIFont systemFontOfSize:17],
                                 NSParagraphStyleAttributeName:paragraphStyle
                                 };
self.textView.typingAttributes = attributes;

总结

代码比较简单，完整项目地址------>CLInputToolbar