计算文本高度

gistfile1.m

- (CGFloat)heighWithFont:(UIFont *)font constrainedToSize:(CGSize)size
{
    return [self sizeWithFont:font constrainedToSize:size].height;
}

- (CGFloat)widthWithFont:(UIFont *)font constrainedToSize:(CGSize)size
{
    return [self sizeWithFont:font constrainedToSize:size].width;
}

- (CGSize)sizeWithFont:(UIFont *)font constrainedToSize:(CGSize)size
{
    CGRect stringRect;
    if ([self respondsToSelector:@selector(boundingRectWithSize:options:attributes:context:)]) {
        stringRect = [self boundingRectWithSize:size
                                        options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading
                                     attributes:@{NSFontAttributeName: font}
                                        context:NULL];
    } else {
        CGSize stringSize = [self sizeWithFont:font constrainedToSize:size];
        stringRect = CGRectMake(0, 0, stringSize.width, stringSize.height);
    }
    return stringRect.size;
}