iOS UILabel 文字竖排显示

iOS UILabel 文字竖排显示

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。

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- (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];

    returnsize;

}



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：

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- (CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines

{

    CGRect textRect = [supertextRectForBounds:bounds limitedToNumberOfLines:numberOfLines];

    switch(self.verticalAlignment) {

        caseVerticalAlignmentTop:

            textRect.origin.y = bounds.origin.y;

            break;

        caseVerticalAlignmentBottom:

            textRect.origin.y = bounds.origin.y + bounds.size.height - textRect.size.height;

            break;

        caseVerticalAlignmentMiddle:

            // Fall through.

        default:

            textRect.origin.y = bounds.origin.y + (bounds.size.height - textRect.size.height) /2.0;

    }

    returntextRect;

}

 

// 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];

    [superdrawTextInRect: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

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/**

*  拆分标题中的中文与非中文

*/

- (NSArray *)splitTitle:(NSString *)title

{

    NSArray *stringItemArray = [[NSMutableArray alloc] init];

    inttype =0;

    if([self isChinese:title index:0]) {

        type =1;

    }else{

        type =0;

    }

    intfromIndex =0;

    inttoIndex =0;

    for(inti = 1; i < 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];

                }

            }

        }

    }

    returnstringItemArray;

}

 //判断是否是中文

- (BOOL)isChinese:(NSString *)str index:(int)index

{

    NSRange range = NSMakeRange(index,1);

    NSString *subString = [str substringWithRange:range];

    constchar*cString = [subString UTF8String];

    if(strlen(cString) ==3) {

        returnYES;

    }else{

        returnNO;

    }

}

b) 处理多个label，非中文的label旋转90度

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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 > 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;

    }

}

这样我们就可以用一些简单的api去实现优雅的竖排文字显示。而不需要复杂的CoreText去实现了。
但是如果是复杂的图文混排，最好还是用CoreText去实现。CoreText的用法以后会介绍。