CoreText 解析富文本实战

CoreText是专门用来处理文字和字体的底层技术。直接和2D 图形渲染引擎打交道。效率非常高。 先看实战效果https://github.com/FSilver/FWDrawView

第一步：配置Config

@interface FWDrawConfig : NSObject

@property(nonatomic,strong)NSString *text;
@property(nonatomic,assign)CGFloat width;
@property(nonatomic,assign)UIFont  *font;
@property(nonatomic,strong)UIColor *textColor;
@property(nonatomic,strong)UIColor *linkColor;
@property(nonatomic,assign)int underLineOfLink;
@property(nonatomic,assign)NSInteger numberOfLines; 
@property(nonatomic,assign)UIEdgeInsets edgInsets;

@end

拿到文本后，先设置文本最大的显示宽度，文本的字体，颜色，文字最大显示行数，文字在控件中上下左右边距。 链接字体的颜色，下划线。

第二步：解析parse

@interface FWDrawParser : NSObject

@property(nonatomic,strong)FWDrawInfo *data;
@property(nonatomic,strong)NSMutableAttributedString *resultAttributeString;
@property(nonatomic,strong)NSDictionary *textAttributeDict;

-(id)initWithConfig:(FWDrawConfig*)config;
-(void)parseEmoji;
-(void)parseUrl;
-(void)parsePhone;
-(void)addLinkWithValue:(id)value range:(NSRange)range;

@end

利用config生成富文本字典，以及富文本呢

-(void)configTextAttributeDictionay
{
    //用一个普通的汉子排版的高度，设置为最低高度，保证中文，英文，表情，间距相等，视觉上舒服
    //float minLineHight = config.font.lineHeight - config.font.descender;
    float minLineHight = _config.font.lineHeight;
    
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    [paragraphStyle setLineSpacing:0];
    [paragraphStyle setMinimumLineHeight:minLineHight];
    paragraphStyle.lineHeightMultiple = 0;
    
    NSDictionary *ats = @{
                          NSFontAttributeName : _config.font,
                          NSForegroundColorAttributeName:_config.textColor,
                          NSParagraphStyleAttributeName : paragraphStyle,
                          };
    _textAttributeDict = ats;
}

-(void)configResultAttributeString
{
    _resultAttributeString = [[NSMutableAttributedString alloc]init];
    NSAttributedString *attributeString = [[NSAttributedString alloc]initWithString:_config.text attributes:_textAttributeDict];
    [_resultAttributeString appendAttributedString:attributeString];
}

第三步：数据data

@interface FWDrawInfo : NSObject

@property(nonatomic,assign)CTFrameRef ctFrame;
@property(nonatomic,assign)CGFloat originHeight; //全部显示完全的高度
@property(nonatomic,assign)CGFloat width;        //实际宽度
@property(nonatomic,assign)CGFloat height;       //实际高度
@property(nonatomic,assign)NSInteger lines;         //文本总行数
@property(nonatomic,assign)NSInteger numberOfLines; //限制行数
@property(nonatomic,assign)UIEdgeInsets edgInsets;
@property(nonatomic,strong)NSDictionary *textAttributeDict;
@property(nonatomic,strong)NSAttributedString *attributedString;

@property(nonatomic,strong)NSArray *emojiArray;  //赋值的时候，计算区域
@property(nonatomic,strong)NSArray *linkArray;   //赋值的时候，计算区域

@end

第四步：绘制data

@class FWDrawView;
@protocol FWDrawViewDelegate <NSObject>

@optional
-(void)didClickFWDraw:(FWDrawView*)draw; //单击
-(void)didLongPressFWDraw:(FWDrawView*)draw;//双击
-(void)didClickFWDraw:(FWDrawView *)draw byLink:(FWDrawLinkInfo*)link; //点击链接

@end

@interface FWDrawView : UIView

@property(nonatomic,weak)id<FWDrawViewDelegate>delegate;
@property(nonatomic,strong)FWDrawInfo *data;

@property(nonatomic,strong)UIColor *linkBgColor;//选中链接后，链接背景色

@property(nonatomic,strong)UIColor *tapColor; //点击View,高亮色
@property(nonatomic,assign)BOOL allowTapGesture; //是否允许单机

@property(nonatomic,assign)BOOL allowLongPressGesture;  //是否允许长按 
@property(nonatomic,strong)UIColor *longPressColor;     //长按View后，view的背景色

@end

绘制方法

-(void)drawRect:(CGRect)rect
{
    [super drawRect:rect];
    
    if(self.data == nil){
        return;
    }
    
    CGContextRef  context = UIGraphicsGetCurrentContext();
    //坐标系coreText --》 UIkit坐标系
    CGContextSetTextMatrix(context, CGAffineTransformIdentity);
    CGContextTranslateCTM(context, 0, self.bounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);
    
    _lastLineOriginY = -1;
    _lastLineRightX = -1;
    if(_data.numberOfLines == 0 || _data.numberOfLines >= _data.lines){
        
        CTFrameDraw(self.data.ctFrame, context);
        
    }else{
        
        [self drawLineByContext:context];
    }
    

    //作用是，画表情
    for (FWDrawEmojiInfo * emoji in self.data.emojiArray) {
        
        
        //转为UI坐标系,表情位置大于有效区域，就break
        float y = _data.height - emoji.drawRect.origin.y - emoji.drawRect.size.height;
        if(y + emoji.drawRect.size.height > _data.height - _data.edgInsets.bottom){
            break;
        }
    
        BOOL drawImage = NO;
        if(_lastLineOriginY == -1 && _lastLineRightX == -1){
            //全部显示
            drawImage = YES;
            
        }else{
            //限制行数
            if(y < _lastLineOriginY){
                //不是最后一行
                drawImage = YES;
            }else if(emoji.drawRect.origin.x + emoji.drawRect.size.width < _lastLineRightX){
                //是最后一行
                 drawImage = YES;
            }
        }
        
        if(drawImage){
            UIImage *image = [UIImage imageNamed:emoji.imageName];
            if(image){
                CGContextDrawImage(context, emoji.drawRect, image.CGImage);
            }
        }
      }
    
    
    //作用是，选中链接后，链接高亮显示
    for (FWDrawLinkInfo *url in self.data.linkArray) {
        
        for (NSValue  *value in url.drawRectArray) {
            
            
            //转为UI坐标系
            CGRect urlRect = [value CGRectValue];
            CGFloat y = _data.height - urlRect.origin.y - urlRect.size.height;
            if( y + urlRect.size.height > _data.height - _data.edgInsets.bottom){
                break;
            }
            
            if(url.isSelected){
            
                CGRect urlRect = [value CGRectValue];
                CGContextSetFillColorWithColor(context,self.linkBgColor.CGColor);
                CGContextFillRect(context , urlRect);
            }
        }
    }
}

完整代码github地址 https://github.com/FSilver/FWDrawView