sizeWithAttributes

    CGSize textSize = CGSizeZero;

    if ([[UIDevice currentDevice].systemVersion floatValue] >= 7.0)

    {

        textSize = [text sizeWithAttributes: @{NSFontAttributeName:_numLabel.font}];

    }

    else

    {

#pragma clang diagnostic push

#pragma clang diagnostic ignored "-Wdeprecated-declarations"

        textSize = [text sizeWithFont:_numLabel.font];

#pragma clang diagnostic pop

    }

sizeWithAttributes

原文：http://www.cnblogs.com/417460188dy/p/4521942.html