纯UILabel实现文字的竖排显示

本文主要是介绍纯UILabel实现文字的竖排显示，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

做iOS开发要经常用到UILabel。UILabel一般只适用一些简单的文字显示。当需要复杂的图文混排的时候，可以用CoreText来做。但是CoreText用法复杂，当我们遇到一些不是很复杂的交互需求时，用CoreText就有点杀鸡用牛刀的意思。这里介绍一下我在项目里遇到的一个案例。
先来看看效果：

这里要求文字都是竖排显示，并且当文字是非汉字的时候又要把文字侧过来以方便阅读。
下面就介绍一下我实现这个需求的过程。

一、计算label的高度

在很多场景下，我们需要事先知道这个label的size，下面这个方法可以计算在已知width、font和label中的text内容的情况下，这个label的高度。

  - (CGSize)getSize:(NSString *)detail font:(UIFont *)font width:( float )width 
 { 
      CGSize constraint = CGSizeMake(width,  20000 .0f); 
      CGSize size = [detail sizeWithFont:font constrainedToSize:constraint lineBreakMode:UILineBreakModeCharacterWrap]; 
      return size; 
 } 
 

利用这个方法也可以简单的实现竖排显示文字，只需要把width参数设置成一个字符的宽度就可以。一般字体大小在14 – 20之间，width参数设置为14.0

二、如何让label置顶或其它

label默认的textAlignment只有UITextAlignmentLeft、UITextAlignmentCenter、UITextAlignmentRight三种。
在需要文字居顶，居底时，UILabel的api就不够用了。不过这个时候我们可以通过重写UILabel的- (CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines方法来实现。代码如下：

  - (CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines 
 { 
      CGRect textRect = [ super textRectForBounds:bounds limitedToNumberOfLines:numberOfLines]; 
      switch (self.verticalAlignment) { 
          case VerticalAlignmentTop: 
              textRect.origin.y = bounds.origin.y; 
              break ; 
          case VerticalAlignmentBottom: 
              textRect.origin.y = bounds.origin.y + bounds.size.height - textRect.size.height; 
              break ; 
          case VerticalAlignmentMiddle: 
              // Fall through. 
          default : 
              textRect.origin.y = bounds.origin.y + (bounds.size.height - textRect.size.height) /  2.0 ; 
      } 
      return textRect; 
 } 
 // 然后在drawTextInRect:方法中使用重新计算的CGRect 
 -( void )drawTextInRect:(CGRect)requestedRect 
 { 
      CGRect actualRect = [self textRectForBounds:requestedRect limitedToNumberOfLines:self.numberOfLines]; 
      [ super drawTextInRect:actualRect]; 
 } 
 

三、竖排显示文字时，如何让汉字竖排，而英文和数字为横排

汉字竖排显示没有压力，但是如果英文也都竖排显示就很难读懂了。
我这里的做法是：
1、拆分label的内容，把汉字、英文拆分开，并放在多个label中显示。
2、英文横排显示，然后把label旋转90度。

代码如下：
a) 拆分内容

  /** 
 *  拆分标题中的中文与非中文 
 */ 
 - (NSArray *)splitTitle:(NSString *)title 
 { 
      NSArray *stringItemArray = [[NSMutableArray alloc] init]; 
      int type =  0 ; 
      if ([self isChinese:title index: 0 ]) { 
          type =  1 ; 
      }  else  { 
          type =  0 ; 
      } 
      int fromIndex =  0 ; 
      int toIndex =  0 ; 
      for ( int i =  1 ; i &amp;lt; title.length; i++) { 
          if (type ==  1 ) { 
              if ([self isChinese:title index:i]) { 
                  if (i == title.length -  1 ) { 
                      StringItem *item = [[StringItem alloc] init]; 
                      item.isChinese = [self isChinese:title index:i]; 
                      item.content = [title substringWithRange:NSMakeRange(fromIndex, title.length - fromIndex)]; 
                      [stringItemArray addObject:item]; 
                      [item release]; 
                  } 
                  toIndex = i; 
              }  else  { 
                  type =  0 ; 
                  StringItem *item = [[StringItem alloc] init]; 
                  item.isChinese = YES; 
                  item.content = [title substringWithRange:NSMakeRange(fromIndex, toIndex - fromIndex +  1 )]; 
                  [stringItemArray addObject:item]; 
                  [item release]; 
                   
                  fromIndex = i; 
                  toIndex = i; 
                  if (i == title.length -  1 ) { 
                      StringItem *item = [[StringItem alloc] init]; 
                      item.isChinese = [self isChinese:title index:i]; 
                      item.content = [title substringWithRange:NSMakeRange(fromIndex, title.length - fromIndex)]; 
                      [stringItemArray addObject:item]; 
                      [item release]; 
                       
                  } 
              } 
          }  else  { 
              if (![self isChinese:title index:i]) { 
                  if (i == title.length -  1 ) { 
                      StringItem *item = [[StringItem alloc] init]; 
                      item.isChinese = [self isChinese:title index:i]; 
                      item.content = [title substringWithRange:NSMakeRange(fromIndex, title.length - fromIndex)]; 
                      [stringItemArray addObject:item]; 
                      [item release]; 
                       
                  } 
                  toIndex = i; 
              }  else  { 
                  type =  1 ; 
                  StringItem *item = [[StringItem alloc] init]; 
                  item.isChinese = NO; 
                  item.content = [title substringWithRange:NSMakeRange(fromIndex, toIndex - fromIndex +  1 )]; 
                  [stringItemArray addObject:item]; 
                  [item release]; 
                   
                  fromIndex = i; 
                  toIndex = i; 
                  if (i == title.length -  1 ) { 
                      StringItem *item = [[StringItem alloc] init]; 
                      item.isChinese = [self isChinese:title index:i]; 
                      item.content = [title substringWithRange:NSMakeRange(fromIndex, title.length - fromIndex)]; 
                      [stringItemArray addObject:item]; 
                      [item release]; 
                  } 
              } 
          } 
      } 
      return stringItemArray; 
 } 
   //判断是否是中文  
 - (BOOL)isChinese:(NSString *)str index:( int )index 
 { 
      NSRange range = NSMakeRange(index,  1 ); 
      NSString *subString = [str substringWithRange:range]; 
      const char  *cString = [subString UTF8String]; 
      if (strlen(cString) ==  3 ) { 
          return YES; 
      }  else  { 
          return NO; 
      } 
 } 
 

b) 处理多个label，非中文的label旋转90度

  CGRect frame = self.frame; 
 UIFont *font = [UIFont systemFontOfSize: 16 ]; 
 float height =  40 ; 
 for (StringItem *item in stringItemArray) { 
      if (item.isChinese) { 
          CGSize size = [self getSize:item.content font:font]; 
          VerticallyAlignedLabel *label = [[VerticallyAlignedLabel alloc] initWithFrame:CGRectMake((frame.size.width - size.width) /  2 , height, size.width, size.height)]; 
          label.verticalAlignment = VerticalAlignmentTop; 
          label.textAlignment = UITextAlignmentCenter; 
          label.textColor = textColor; 
          label.font = font; 
          label.backgroundColor = [UIColor clearColor]; 
          [label setLineBreakMode:UILineBreakModeWordWrap]; 
          label.text = item.content; 
           
          label.numberOfLines =  0 ; 
           
          [self addSubview:label]; 
          height = height + label.frame.size.height; 
      }  else  { 
          CGSize size = [self getVerSize:item.content font:font]; 
          VerticallyAlignedLabel *label = [[VerticallyAlignedLabel alloc] initWithFrame:CGRectMake((frame.size.width - size.height) /  2 , height, size.height &amp;gt; frame.size.height - height ? frame.size.height - height : size.width, size.height)]; 
          label.verticalAlignment = VerticalAlignmentTop; 
          label.textAlignment = UITextAlignmentCenter; 
          label.textColor = textColor; 
          label.font = font; 
          label.backgroundColor = [UIColor clearColor]; 
          [label setLineBreakMode:UILineBreakModeWordWrap]; 
          label.text = item.content; 
           
          label.numberOfLines =  1 ; 
           
          label.transform = CGAffineTransformMakeRotation(M_PI_2); 
           
          label.frame = CGRectMake((frame.size.width - label.frame.size.width) /  2 , height, label.frame.size.width, label.frame.size.height); 
          [self addSubview:label]; 
          height = height + label.frame.size.height; 
      } 
 } 
 