在iOS 7中获取NSString高度

Question

我使用下面的代码从字符串长度计算标签的高度.我使用xcode 5.0,它在iOS 6模拟器中工作正常,但它在iOS 7中运行不佳.

NSString* str = [[array objectAtIndex:i]valueForKey:@"comment"];

CGSize size = [className sizeWithFont:[UIFont systemFontOfSize:15]   
 constrainedToSize:CGSizeMake(300, MAXFLOAT) lineBreakMode:UILineBreakModeWordWrap];

Height_1 = size.height;

如果iOS 7有任何解决方案,那么请帮忙.提前致谢

Answer 1

这里有一个我用来计算iOS 6和iOS 7高度的解决方案,我已经通过了几个参数来使它可以重用.

#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedAscending)

/**
*  This method is used to calculate height of text given which fits in specific width having    font provided
*
*  @param text       Text to calculate height of
*  @param widthValue Width of container
*  @param font       Font size of text
*
*  @return Height required to fit given text in container
*/

+ (CGFloat)findHeightForText:(NSString *)text havingWidth:(CGFloat)widthValue andFont:(UIFont *)font
{
    CGFloat result = font.pointSize + 4;
    if (text)
    {
        CGSize textSize = { widthValue, CGFLOAT_MAX };       //Width and height of text area
        CGSize size;
        if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"7.0"))
        {
            //iOS 7
            CGRect frame = [text boundingRectWithSize:textSize
                                          options:NSStringDrawingUsesLineFragmentOrigin
                                       attributes:@{ NSFontAttributeName:font }
                                          context:nil];
            size = CGSizeMake(frame.size.width, frame.size.height+1);
        }
        else
        {
            //iOS 6.0
            size = [text sizeWithFont:font constrainedToSize:textSize lineBreakMode:NSLineBreakByWordWrapping];
        }
        result = MAX(size.height, result); //At least one row
    }
    return result;
}

希望这有所帮助,是的任何建议表示赞赏.快乐编码:)

对于iOS 7及以上版本,请使用以下方法.

+ (CGSize)findHeightForText:(NSString *)text havingWidth:(CGFloat)widthValue andFont:(UIFont *)font {
    CGSize size = CGSizeZero;
    if (text) {
        //iOS 7
        CGRect frame = [text boundingRectWithSize:CGSizeMake(widthValue, CGFLOAT_MAX) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{ NSFontAttributeName:font } context:nil];
        size = CGSizeMake(frame.size.width, frame.size.height + 1);
    }
    return size;
}