https://segmentfault.com/q/1010000004452279
利用YYText可以解决这个问题 YYLabel.truncationToken
- (void)viewDidLoad {
[super viewDidLoad];
//代码来自:YYText示例demo
NSMutableAttributedString *text = [NSMutableAttributedString new];
UIFont *font = [UIFontsystemFontOfSize:16];
//添加文本
NSString *title = @"豫章故郡，洪都新府。星分翼轸，地接衡庐。襟三江而带五湖，控蛮荆而引瓯越。物华天宝，龙光射牛斗之墟；人杰地灵，徐孺下陈蕃之榻。雄州雾列，俊采星驰。台隍枕夷夏之交，宾主尽东南之美。都督阎公之雅望，棨戟遥临；宇文新州之懿范，襜帷暂驻。十旬休假，胜友如云；千里逢迎，高朋满座。腾蛟起凤，孟学士之词宗；紫电青霜，王将军之武库。家君作宰，路出名区；童子何知，躬逢胜饯。时维九月，序属三秋。潦水尽而寒潭清，烟光凝而暮山紫。俨骖騑于上路，访风景于崇阿。临帝子之长洲，得仙人之旧馆。层台耸翠，上出重霄；飞阁流丹，下临无地。鹤汀凫渚，穷岛屿之萦回；桂殿兰宫，列冈峦之体势。";
[text appendAttributedString:[[NSAttributedString alloc] initWithString:titleattributes:nil]];
text.yy_font = font ;
_label = [YYLabel new];
_label.userInteractionEnabled =YES;
_label.numberOfLines =0;
_label.textVerticalAlignment = YYTextVerticalAlignmentTop;
_label.frame = CGRectMake(60,60, 260,260);
_label.attributedText = text;
[self.viewaddSubview:_label];
_label.layer.borderWidth =0.5;
_label.layer.borderColor = [UIColorcolorWithRed:0.000green:0.463blue:1.000alpha:1.000].CGColor;
[selfaddSeeMoreButton];
}
- (void)addSeeMoreButton {
__weaktypeof(self) _self =self;
NSMutableAttributedString *text = [[NSMutableAttributedString alloc] initWithString:@"...more"];
YYTextHighlight *hi = [YYTextHighlight new];
[hi setColor:[UIColorcolorWithRed:0.578green:0.790blue:1.000alpha:1.000]];
hi.tapAction = ^(UIView *containerView,NSAttributedString *text,NSRange range, CGRect rect) {
YYLabel *label = _self.label;
[label sizeToFit];
};
[text yy_setColor:[UIColorcolorWithRed:0.000green:0.449blue:1.000alpha:1.000]range:[text.stringrangeOfString:@"more"]];
[text yy_setTextHighlight:hirange:[text.string rangeOfString:@"more"]];
text.yy_font =_label.font;
YYLabel *seeMore = [YYLabel new];
seeMore.attributedText = text;
[seeMore sizeToFit];
NSAttributedString *truncationToken = [NSAttributedStringyy_attachmentStringWithContent:seeMorecontentMode:UIViewContentModeCenterattachmentSize:seeMore.frame.sizealignToFont:text.yy_fontalignment:YYTextVerticalAlignmentCenter];
_label.truncationToken = truncationToken;
}
Core Text
- (void)drawTextInRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
//将当前context的坐标系进行flip,否则上下颠倒
CGAffineTransform flipVertical = CGAffineTransformMake(1,0,0,-1,0,self.bounds.size.height);
CGContextConcatCTM(context, flipVertical);
//设置字形变换矩阵为CGAffineTransformIdentity，也就是说每一个字形都不做图形变换
CGContextSetTextMatrix(context, CGAffineTransformIdentity);
NSString *attrStr = self.resultAttributedString.string;
NSRange range = NSMakeRange(0, attrStr.length);
NSDictionary *dic = [self.resultAttributedString attributesAtIndex:0 effectiveRange:&range];
NSMutableParagraphStyle *ps = [dic objectForKey:NSParagraphStyleAttributeName];
BOOL truncatTail = NO;
if(ps.lineBreakMode == NSLineBreakByTruncatingTail) {
truncatTail = YES;
}
CTFramesetterRef framesetter = [self framesetter];
CGMutablePathRef pathRef = CGPathCreateMutable();
CGPathAddRect(pathRef,NULL , CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height));
_textFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), pathRef,NULL );
NSInteger numberOfLines = [self numberOfDisplayedLines];
CGSize tempSize = self.frame.size;
CGSize trueSize = [self getLLLLabelSize];
if (_textFrame) {
if (numberOfLines > 0 && tempSize.height < trueSize.height) {
CFArrayRef lines = CTFrameGetLines(_textFrame);
CGPoint lineOrigins[numberOfLines];
CTFrameGetLineOrigins(_textFrame, CFRangeMake(0, numberOfLines), lineOrigins);
NSAttributedString *attributedString = self.resultAttributedString;
for (CFIndex lineIndex = 0; lineIndex < numberOfLines; lineIndex++) {
CGPoint lineOrigin = lineOrigins[lineIndex];
CGContextSetTextPosition(context, lineOrigin.x, lineOrigin.y);
CTLineRef line = CFArrayGetValueAtIndex(lines, lineIndex);
BOOL shouldDrawLine = YES;
if (lineIndex == numberOfLines - 1 ) {
// Does the last line need truncation?
CFRange lastLineRange = CTLineGetStringRange(line);
if (lastLineRange.location + lastLineRange.length < attributedString.length) {
CTLineTruncationType truncationType = kCTLineTruncationEnd;
//加省略号的位置
NSUInteger truncationAttributePosition = lastLineRange.location + lastLineRange.length - 1;
//获取省略号位置的字符串属性
NSDictionary *tokenAttributes = [attributedString attributesAtIndex:truncationAttributePosition
effectiveRange:NULL];
//初始化省略号的属性字符串
NSAttributedString *tokenString = [[NSAttributedString alloc] initWithString:kEllipsesCharacter
attributes:tokenAttributes];
//创建一行
CTLineRef truncationToken = CTLineCreateWithAttributedString((CFAttributedStringRef)tokenString);
NSMutableAttributedString *truncationString = [[attributedString attributedSubstringFromRange:NSMakeRange(lastLineRange.location, lastLineRange.length)] mutableCopy];
if (lastLineRange.length > 0) {
// Remove last token
[truncationString deleteCharactersInRange:NSMakeRange(lastLineRange.length - 1, 1)];
}
[truncationString appendAttributedString:tokenString];
//创建省略号的行
CTLineRef truncationLine = CTLineCreateWithAttributedString((CFAttributedStringRef)truncationString);
// 在省略号行的末尾加上省略号
CTLineRef truncatedLine = CTLineCreateTruncatedLine(truncationLine, rect.size.width, truncationType, truncationToken);
if (!truncatedLine) {
// If the line is not as wide as the truncationToken, truncatedLine is NULL
truncatedLine = CFRetain(truncationToken);
}
CFRelease(truncationLine);//CF得自己释放，ARC的不会释放
CFRelease(truncationToken);
CTLineDraw(truncatedLine, context);
CFRelease(truncatedLine);
shouldDrawLine = NO;
}
}
if(shouldDrawLine) {
CTLineDraw(line, context);
}
}
} else {
CTFrameDraw(_textFrame,context);
}
}
CGContextRestoreGState(context);
}