精确计算文本所占的行数
2021-05-26 本文已影响0人
杨继磊
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;
}