NSArray排序

方法一，

系统自带的数组升序排序

[NSArray *allkeys3=[sellDictallKeys];

 // 默认为升序

 NSArray *allkeysSortAsc=[allkeys3sortedArrayUsingSelector:@selector(compare:)];

方法二，

   //取出data中的keys

            NSArray *allKeys=[dataTempallKeys];

            //keys升序排列

            NSArray *allkeysAsc=[allKeyssortedArrayUsingSelector:@selector(compare:)];

            //keys降序排列

            NSSortDescriptor *sd1=[NSSortDescriptorsortDescriptorWithKey:nilascending:NO];//yes升序   no  降序

            NSArray  *allkeysDesc=[allKeyssortedArrayUsingDescriptors:[NSArrayarrayWithObjects:sd1, nil]];