Objective-c NSArrray数据操作

数据源：NSArray *array = @[@10.1,@10.5,@12,@9.2,@109.4,@39.3];

1.获得最大值

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

//关键字 @max 通过指定数据类型得到对应的NSNumber数据

2.获得最小值

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

3.获得数据和

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

4.获得数据平均值

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

5.返回数组中大于3的元素

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

NSArray *preArray = [array filteredArrayUsingPredicate:pre];

6.从小到大排序

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

7.从大到小排序

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

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

};

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