如何根据文本计算TextView高度

Question

我使用下面的代码计算文本的高度,然后为UILabel和设置此高度UITextView

CGSize targetSize = CGSizeMake(300, CGFLOAT_MAX);
NSString *message = @"The Internet connection appears to be offline.";

NSStringDrawingContext *context = [[NSStringDrawingContext alloc] init];
CGSize boundingBox = [message boundingRectWithSize:targetSize
                                              options:NSStringDrawingUsesLineFragmentOrigin
                                           attributes:@{NSFontAttributeName:FontOpenSanWithSize(14)}
                                              context:context].size;

CGSize size = CGSizeMake(ceil(boundingBox.width), ceil(boundingBox.height));
// it will return size:width = 299 and size height 20
// => if I use this height and set for UILabel, it can display full content
// => if I use this height and set for UITextView, it can not display full content 

这是完美的工作,UILabel但UITextView有时它计算错误.
我认为问题发生的原因是填充(左,右)UITextView大于UILabel.
那么如何计算出正确的文本大小呢UITextView？任何帮助或建议将非常感谢.

如下面的描述图像
具有相同的大小(300),相同的字体,相同的文字,但UITextView显示在2行,但UILabel在1行.而我的计算高度代码返回20,它不足以显示2行,因此UITextView无法显示完整内容

之所以我需要计算UITextView基础文本的高度,因为我UITextView在弹出窗口中.弹出高度取决于TextView高度

Answer 1

您可以尝试两件事:

1. 组 textView.textContainerInset = UIEdgeInsetsZero
2. 组 textView.textContainer.lineFragmentPadding = 0

通过这些操作,您可以摆脱textView中的所有填充,当其宽度与标签的宽度匹配时,高度也是相同的.

这是一个示例代码,您可以将其放在一个空的viewController中并自己测试:

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    NSString *text = @"The internet connection appears to be offline.";
    CGFloat width = 100.f;

    UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(20, 20, width, 300)];
    textView.font = [UIFont fontWithName:@"AvenirNext-Regular" size:12.f];
    textView.text = text;
    [self.view addSubview:textView];

    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(20 + width, 20, width, 300)];
    label.numberOfLines = 0;
    label.font = [UIFont fontWithName:@"AvenirNext-Regular" size:12.f];
    label.text = text;
    [self.view addSubview:label];

    // Getting rid of textView's padding
    textView.textContainerInset = UIEdgeInsetsZero;
    textView.textContainer.lineFragmentPadding = 0;

    // Setting height of textView to its contentSize.height
    CGRect textViewFrame = textView.frame;
    textViewFrame.size = textView.contentSize;
    textView.frame = textViewFrame;

    // Setting height of label accorting to it contents and width
    CGRect labelFrame = label.frame;
    labelFrame.size = [label sizeThatFits:CGSizeMake(width, HUGE_VALF)];
    labelFrame.size.width = width;
    label.frame = labelFrame;

    NSLog(@"Label bounds: %@", NSStringFromCGRect(label.bounds));
    NSLog(@"TextView bounds: %@", NSStringFromCGRect(textView.bounds));

    // Visualizing final effect with borders
    textView.layer.borderColor = [UIColor redColor].CGColor;
    textView.layer.borderWidth = 1.f;
    label.layer.borderColor = [UIColor greenColor].CGColor;
    label.layer.borderWidth = 1.f;
}

控制台输出:

2016-09-01 14:29:06.118 stack39268477[943:243243] Label bounds: {{0, 0}, {100, 66}}
2016-09-01 14:29:06.119 stack39268477[943:243243] TextView bounds: {{0, 0}, {100, 66}}

Answer 2

您无需UITextview根据文本计算高度.

只需更改框架并设置高度,如下所示:

textview.size.height = textview.contentSize.height;

这很容易解决.我希望这可以帮助你.

Answer 3

这会计算任何字符串的大小，无论您是否将它们放在文本视图中。

let frame = NSString(string: yourText).boundingRect(
    with: CGSize(width: yourDesiredWidth, height: .infinity),
    options: [.usesFontLeading, .usesLineFragmentOrigin],
    attributes: [.font : yourFont],
    context: nil)

let height = frame.size.height