计算UITextField、UItextView的高度

- (int)getAttributedStringHeightWidthValue:(int)width byAtt:(NSMutableAttributedString *)attributedString
{
    
    
    int total_height = 0;
    
    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attributedString);    //string 为要计算高度的NSAttributedString
    CGRect drawingRect = CGRectMake(0, 0, width, 100000);  //这里的高要设置足够大
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathAddRect(path, NULL, drawingRect);
    CTFrameRef textFrame = CTFramesetterCreateFrame(framesetter,CFRangeMake(0,0), path, NULL);
    CGPathRelease(path);
    CFRelease(framesetter);
    
    NSArray *linesArray = (NSArray *) CTFrameGetLines(textFrame);
    
    CGPoint origins[[linesArray count]];
    CTFrameGetLineOrigins(textFrame, CFRangeMake(0, 0), origins);
    
    int line_y = (int) origins[[linesArray count] -1].y;  //最后一行line的原点y坐标
    CGSize size[[linesArray count]];
    int line_height=(int) size[[linesArray count]-1].height;
    
    CGFloat ascent;
    CGFloat descent;
    CGFloat leading;
    
    CTLineRef line = (__bridge CTLineRef) [linesArray objectAtIndex:[linesArray count]-1];
    CTLineGetTypographicBounds(line, &ascent, &descent, &leading);
    
    total_height = 100000 + line_height - line_y + (int) descent +1;//+1为了纠正descent转换成int小数点后舍去的值
    
    CFRelease(textFrame);
    
    return total_height;
    
}