NSTableView 文字过长的处理代码

如果在 NSTableView 里需要显示的文字太多，就需要只显示首尾，中间用 …… 代替。代码如下

NSString *setByTrcanateWithAttributeForWidth(NSString *s,NSDictionary *attr,float wid,NSLineBreakMode truncateMode)
{
    NSSize textSize = [s sizeWithAttributes:attr];
    if(textSize.width <= wid)
    {
        return s;
    }
    
    NSMutableString *currString = [NSMutableString string];
    NSRange rangeToCut = {0,0};
    if(truncateMode == NSLineBreakByTruncatingTail)
    {
        rangeToCut.location = [s length] - 1;
        rangeToCut.length = 0;
    }
    else if(truncateMode == NSLineBreakByTruncatingHead)
    {
        rangeToCut.location = 0;
        rangeToCut.length = 1;
    }
    else 
    {
        rangeToCut.location = [s length]/2;
        rangeToCut.length = 2;
    }
    
    while (textSize.width > wid) 
    {
        if(truncateMode != NSLineBreakByTruncatingHead && rangeToCut.location <=1)
            return @"....";
        [currString setString: s];
        [currString replaceCharactersInRange:rangeToCut withString:@"...."];
        textSize =[currString sizeWithAttributes: attr];
        rangeToCut.length++;
        if(truncateMode == NSLineBreakByTruncatingTail)
        {
            rangeToCut.location--;
        }
        else if((rangeToCut.length && 1) != 1)
        {
            rangeToCut.location--;
        } 
        else if((rangeToCut.location < 0) || (rangeToCut.location +rangeToCut.length) >[s length])
        {
            return @"....";
            
        }
    }
    return currString;
}