Obj-C-检测textView换行符？

Question

当用户在我的 textView 中键入时，我想知道新行何时开始，因为我想在发生这种情况时更改我的 textView 的高度。也就是说，如果按下返回按钮，我知道如何完成此操作 - 但如果新行只是自动开始（例如，仅仅因为用户不断输入而开始新行），这似乎并不那么简单。当点击“返回”时，我在下面使用的代码可以成功运行 - 但我似乎无法让它检测到任何类型的换行。

希望我的措辞足够好。谢谢！

 - (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range
 replacementText:(NSString *)text
{


    if ([text isEqualToString:@"\n"]) {
        self.replyField.text=[NSString stringWithFormat:@"%@\n",self.replyField.text];

        CGFloat fixedWidth = self.replyField.frame.size.width;
        CGSize newSize = [self.replyField sizeThatFits:CGSizeMake(fixedWidth, MAXFLOAT)];
        CGRect newFrame = self.replyField.frame;
        newFrame.size = CGSizeMake(fmaxf(newSize.width, fixedWidth), newSize.height);
        self.replyField.frame = newFrame;

        CGRect newFrame1 = self.upView.frame;

        NSLog(@"WHAT IS THE NEW HEIGHT %f", newFrame1.size.height);

         self.upView.frame = CGRectOffset(self.upView.frame, 0, -15);

        return NO;

    }

    // For any other character return TRUE so that the text gets added to the view
    return YES;
}

Answer 1

我不确定这是否会有所帮助，因为我对 obj-c 也很陌生，但试一试

-(void)textViewDidChange:(UITextView *)textView
  {
    CGFloat fixedWidth = textView.frame.size.width;
    CGSize newSize = [textView sizeThatFits:CGSizeMake(fixedWidth, MAXFLOAT)];
    CGRect newFrame = textView.frame;
    newFrame.size = CGSizeMake(fmaxf(newSize.width, fixedWidth), 
    newSize.height);
    textView.frame = newFrame;
 }

确保您也禁用滚动

   textview.scrollEnabled = NO;

Answer 2

要检测行数的变化，您可以使用 KVO，正如@rmaddy 建议的那样。

- (void)viewDidLoad {
     [textView addObserver:self forKeyPath:@"contentSize" options:NSKeyValueObservingOptionOld | NSKeyValueObservingOptionNew context:nil];
}

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
    if (change != nil && [keyPath isEqualToString:@"contentSize"] && [object isKindOfClass:UITextView.class]) {
        NSNumber *oldValue = change[NSKeyValueChangeOldKey];
        NSNumber *newValue = change[NSKeyValueChangeNewKey];
        //Do anything you need with the height values here
    }
}

---

迅速

override func viewDidLoad() {
    textView.addObserver(self, forKeyPath: "contentSize", options: [.old, .new], context: nil)
}

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    guard let change = change, keyPath == "contentSize" && object is UITextView else {
        return
    }

    let oldHeight = (change[.oldKey] as! CGSize).height
    let newHeight = (change[.newKey] as! CGSize).height

    //Do anything you need with the height values here
}

deinit {
    // iOS10 was crashing for me when I didn't explicitly remove
    // the observer before destroying the containing object
    inputTextView.removeObserver(self, forKeyPath: "contentSize", context: nil)
}

Answer 3

试试这个：

对于动态更改 UITextView 高度，您可以创建 height 约束的属性并将其设置/连接到来自 storyboard 的 textview 高度约束。

@property (weak, nonatomic) IBOutlet NSLayoutConstraint *txtViewHeightConstraint;

然后在添加didChange 之后检查textview 输入

-(void)textViewDidChange:(UITextView *)textView
{
     [self SetupTextField] ;
}

- (void)SetupTextField{

    CGRect newFrame = self.txtInfo.frame;
    newFrame.size.height = self.txtInfo.contentSize.height;


    NSLog(@"NEW HEIGHT %f", newFrame1.size.height);

    if (newFrame.size.height < 100.0) { // if condition is optional 
        self.txtViewHeightConstraint.constant = newFrame.size.height ;
    }
}

检查屏幕截图以了解textview 的设置高度限制