values of type NSInteger should not be used as format arguments; 关于Xcode中烦人的32位与64位警告处理方法.

http://stackoverflow.com/questions/16075559/why-does-an-nsinteger-variable-have-to-be-casted-to-long-when-used-as-a-format-a

老老实实按Xcode的提示来处理

添加ld%,  添加(long)

这样才能保证在32位和64位上都不会出现警告.

[NSString stringWithFormat:@"%ld", (long)_filterIndex]