數(shù)據(jù)源：NSArray *array = @[@10.1,@10.5,@12,@9.2,@109.4,@39.3];

1.獲得最大值

NSNumber *max = [array valueForKeyPath:@"@max.floatValue"];

//關(guān)鍵字 @max 通過指定數(shù)據(jù)類型得到對應(yīng)的NSNumber數(shù)據(jù)

2.獲得最小值

NSNumber *min = [array valueForKeyPath:@"@min.floatValue"];

3.獲得數(shù)據(jù)和

NSNumber *sum = [array valueForKeyPath:@"@sum.floatValue"];

4.獲得數(shù)據(jù)平均值

NSNumber *avg = [array valueForKeyPath:@"@avg.floatValue"];

5.返回?cái)?shù)組中大于3的元素

NSPredicate *pre = [NSPredicate predicateWithFormat:@"self > 20"];

NSArray *preArray = [array filteredArrayUsingPredicate:pre];

6.從小到大排序

NSArray *sortedArray = [array sortedArrayUsingSelector:@selector(compare:)];

7.從大到小排序

NSComparator comptr = ^(id obj1, id obj2){

return (-1)*[obj1 compare:obj2];

};

NSArray *revertSortedArray = [array sortedArrayWithOptions:NSSortStable usingComparator:comptr];