ios7中的字符串(格式:)崩溃——需要一个替代。线程1:EXC_BAD_ACCESS(代码=1，地址=0x10)

The String(format:) method is crashing my app in iOS 7 but it works fine in iOS 8. Is there anything I can use to get the same effect here that works in both?The String(format:) method is crashing my app i