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精确计算文本所占的行数

精确计算文本所占的行数

作者: 杨继磊 | 来源:发表于2021-05-26 17:31 被阅读0次

    在 iOS 开发过程中,需要计算一段文字所占的行数,试了几种方式都很难准确计算。

    通过coreText 框架,去精确计算一段文本所占的行数。

    + (NSArray *)getLinesArrayOfStringInLabel:(NSString *)string font:(UIFont *)font andLableWidth:(CGFloat)lableWidth{
        
        CTFontRef myFont = CTFontCreateWithName(( CFStringRef)([font fontName]), [font pointSize], NULL);
        NSMutableAttributedString *attStr = [[NSMutableAttributedString alloc] initWithString:string];
        [attStr addAttribute:(NSString *)kCTFontAttributeName value:(__bridge  id)myFont range:NSMakeRange(0, attStr.length)];
        CFRelease(myFont);
        CTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString(( CFAttributedStringRef)attStr);
        CGMutablePathRef path = CGPathCreateMutable();
        CGPathAddRect(path, NULL, CGRectMake(0,0,lableWidth,100000));
        CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, 0), path, NULL);
        NSArray *lines = ( NSArray *)CTFrameGetLines(frame);
        NSMutableArray *linesArray = [[NSMutableArray alloc]init];
        for (id line in lines) {
            CTLineRef lineRef = (__bridge  CTLineRef )line;
            CFRange lineRange = CTLineGetStringRange(lineRef);
            NSRange range = NSMakeRange(lineRange.location, lineRange.length);
            NSString *lineString = [string substringWithRange:range];
            CFAttributedStringSetAttribute((CFMutableAttributedStringRef)attStr, lineRange, kCTKernAttributeName, (CFTypeRef)([NSNumber numberWithFloat:0.0]));
            CFAttributedStringSetAttribute((CFMutableAttributedStringRef)attStr, lineRange, kCTKernAttributeName, (CFTypeRef)([NSNumber numberWithInt:0.0]));
            [linesArray addObject:lineString];
        }
        
        CGPathRelease(path);
        CFRelease( frame );
        CFRelease(frameSetter);
        return (NSArray *)linesArray;
    }
    
    
    

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