ios - 如何根据内容调整 UITextView 的大小，宽度固定

Question

我必须以编程方式创建一个 UITextView，但在设置它的大小时遇到​​了一些麻烦。

假设我有一个句子，多行：

s = @"Hello World\nHello World\nHello World\n";

现在我想弄清楚我需要显示它的高度，并相应地设置我的 UITextView 的高度（需要固定宽度）。以下是我的代码：

    CGSize size = [text sizeWithFont:_FONT_MYRIADPRO(20.0f) constrainedToSize:CGSizeMake(300, 1000)];
    
    _textBox.text = text;
    _textBox.frame = CGRectMake(10, 10, 300, size.height);
    _textBox.font = _FONT_MYRIADPRO(20.0f);
    _textBox.textColor = _COLOR_BLACK;
    _textBox.backgroundColor = _COLOR_BLUE_DARK;

    self.frame = CGRectMake(0, 0, 320, _textBox.frame.size.height + 2 * 10);

     [self addSubview:_textBox];

然而，结果是这样的：

我尝试了许多其他方法，例如调用

[_textBox sizeToFit]

这也失败了，因为我想修复宽度。

我也试过

    NSAttributedString *titleText = [[NSAttributedString alloc] initWithString:text attributes:@{NSFontAttributeName: _FONT_MYRIADPRO(20.0f)}];
    CGRect bound = [titleText boundingRectWithSize:CGSizeMake(300, 1000) options:NSStringDrawingUsesLineFragmentOrigin context:nil];
        
    _textBox.text = text;
    _textBox.frame = CGRectMake(10, 10, 300, bound.size.height);

它也失败了，结果与上图相同。

有人可以帮我吗？

Answer 1

我为这个案例做了一些测试。我认为我们最好为高度添加下降器和前导。下行和前导的详细含义请参考https://developer.apple.com/library/ios/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/Introduction/Introduction.html。

我的示例代码如下：

//
//  RootViewController.m
//  TextViewSize
//
//  Created by AnkyHe on 11/13/13.
//  Copyright (c) 2013 Gery Studio. All rights reserved.
//
#import <QuartzCore/QuartzCore.h>

#import "RootViewController.h"

#define TextFont ([UIFont systemFontOfSize:20.0f])

static NSString *textContent = nil;
static NSUInteger const LineNum = 10;

@interface RootViewController ()

@property (nonatomic, weak)  UITextView *textView;

@end

@implementation RootViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
  // Do any additional setup after loading the view.

    NSMutableArray *lines = [[NSMutableArray alloc] initWithCapacity:LineNum];
    for (int i = 0; i < LineNum; ++i) {
        [lines addObject:[NSString stringWithFormat:@"%d Hello world", i]];
    }

    textContent = [lines componentsJoinedByString:@"\n"];

    self.view.backgroundColor = [UIColor whiteColor];

    UITextView *textView = [[UITextView alloc] init];
    self.textView = textView;
    self.textView.text = textContent;
    self.textView.font = TextFont;
    [self.view addSubview:self.textView];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];

    CGRect textRect = [textContent boundingRectWithSize:CGSizeMake(300, 1000)
                                                options:NSStringDrawingUsesLineFragmentOrigin
                                             attributes:@{NSFontAttributeName:TextFont}
                                                context:nil];

    CGSize size = textRect.size;
    self.textView.frame = CGRectMake(0, 0, 300, size.height + TextFont.descender + TextFont.leading);
    self.textView.center = CGPointMake(CGRectGetMidX(self.view.bounds), CGRectGetMidY(self.view.bounds));
}

@end

输出如下：