iOS文字排版问题总结

1、UILabel行间距问题：设计师要求UILabel要有行间距，但是UILabel是没有这么一个直接暴露的属性的，想要修改lineSpacing，我们需要借助NSAttributedString来实现，需要注意计算文字上下留白，示意代码：

NSMutableParagraphStyle *paragraphStyle = [NSMutableParagraphStyle new];
paragraphStyle.lineSpacing = 10 - (label.font.lineHeight - label.font.pointSize);
NSMutableDictionary *attributes = [NSMutableDictionary dictionary];
[attributes setObject:paragraphStyle forKey:NSParagraphStyleAttributeName];
label.attributedText = [[NSAttributedString alloc] initWithString:label.text attributes:attributes];

2、UILabel内边距问题：自定义UILabel，然后重写drawTextInRect，示意代码：

import "CustomLabel.h"

@implementation CustomLabel

• (instancetype)initWithFrame: (CGRect)frame {
  if (self = [super initWithFrame: frame]) {
  _textInsets = UIEdgeInsetsZero;
  }
  }
• (void)drawTextInRect: (CGRect)rect {
  [super drawTextInRect: UIEdgeInsetsInsetRect(rect, _textInsets)];
  }
  @end

3、YYLabel、YYText

4、UITextView行间距问题，光标问题：

可以使用，
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
paragraphStyle.headIndent = 15; // <--- indention if you need it
paragraphStyle.firstLineHeadIndent = 15;
paragraphStyle.lineSpacing = 7; // <--- magic line spacing here!
NSDictionary *attrsDictionary =
@{ NSParagraphStyleAttributeName: paragraphStyle }; // <-- there are many more attrs, e.g NSFontAttributeName
self.textView.attributedText = [[NSAttributedString alloc] initWithString:@"Hello World over many lines!" attributes:attrsDictionary];
或者可以创建一个重新实现[UITextView styleString]的子类：
@implementation MBTextView

• (id)styleString {
  return [[super styleString] stringByAppendingString:@"; line-height: 1.2em"];
  }
  @end

5、字间距问题：

NSString *labelText = label.text;
NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:labelText attributes:@{NSKernAttributeName:@(space)}];
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
[attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [labelText length])];
label.attributedText = attributedString;
[label sizeToFit];

6、行高计算：

使用 string.boundingRect 方法。