自动获取UILabel高度

在iOS 7之前，常用下面这个方法计算文本高度

sizeWithFont:constrainedToSize:lineBreakMode:（Deprecated in iOS 7.0）

但是到了iOS 7 之后，这个方法就不建议使用了。提示用下面这个方法：

boundingRectWithSize:options:attributes:context:（Available in iOS 7.0 and later.）

-(CGSize)GetHeightDyanamic:(UILabel*)lbl
{
    NSRange range = NSMakeRange(0, [lbl.text length]);
    CGSize constraint;
        constraint= CGSizeMake(287 ,MAXFLOAT);
    CGSize size;
    NSString *ver = [[UIDevice currentDevice] systemVersion];
    float ver_float = [ver floatValue];
    if (ver_float>6.0) {//版本
        NSDictionary *attributes = [lbl.attributedText attributesAtIndex:0 effectiveRange:&range];
        CGSize boundingBox = [lbl.text boundingRectWithSize:constraint options: NSStringDrawingUsesLineFragmentOrigin attributes:attributes context:nil].size;
        
        size = CGSizeMake(ceil(boundingBox.width), ceil(boundingBox.height));
    }
    else{
        
        
        size = [lbl.text sizeWithFont:[UIFont fontWithName:@"Helvetica" size:14] constrainedToSize:constraint lineBreakMode:NSLineBreakByWordWrapping];
    }
    return size;
}

//使用方法     UILabel *_lblSelectedCountryNames;

        _lblSelectedCountryNames.text=[ArryData componentsJoinedByString:@"
"];
        CGSize size=[self GetHeightDyanamic:_lblSelectedCountryNames];
        _lblSelectedCountryNames.frame=CGRectMake(16, 240, 287, size.height);