[oc学习笔记]数组的遍历和排序

 1         //数组的遍历(可变数组举例)

 2         //for遍历

 3         NSMutableArray *aa = [NSMutableArray array];

 4         [aa addObjectsFromArray:@[@"ss",@"ddd",@"sad"]];

 5         for (int i = 0;  i < aa.count; i++) {

 6             NSLog(@"%@",[aa objectAtIndex:i]);

 7         }

 8         //快速遍历

 9         for (id obj in aa) {

10             NSLog(@"%@",obj);

11         }

12         //代码块遍历

13         // obj是对象 idx是下标 stop是停止标志

14         [aa enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {

15             NSLog(@"%@",obj);

16             NSLog(@"%@",[aa objectAtIndex:idx]);

17         }];

18         //迭代器遍历

19         //将数组元素存放进迭代器

20         NSEnumerator *en = [aa objectEnumerator];

21         id obj = nil;//创建一个对象接受返回对象

22         while (obj = [en nextObject]) {

23             NSLog(@"%@",obj);

24         }

25         //反向迭代器遍历

26         NSEnumerator *en1 = [aa reverseObjectEnumerator];

27         id obj1 = nil;

28         while (obj1 = [en1 nextObject]) {

29             NSLog(@"%@",obj1);

30         }

31         

32         

33         //排序(可变数组举例)

34         //可变数组排序的方法无返回值 不可变数组的排序有返回值

35         //选择器排序

36         //compare方法尽限于比较元素是字符时 ，如有另外的比较 请另写比较方法 返回值（NSComparisonResult）

37         [aa sortUsingSelector:@selector(compare:)];

38         //代码块排序

39         //根据实际情况写判断方法

40         [aa sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {

41             return [obj1 compare:obj2];

42         }];

43         //比较描述器排序

44         //对多个条件进行排序比较便利

45         Person *p1 = [[Person alloc]init];

46         p1.name = @"ss";

47         p1.age = @"16";

48         

49         Person *p2 = [[Person alloc]init];

50         p2.name = @"dd";

51         p2.age = @"14";

52         

53         Person *p3 = [[Person alloc]init];

54         p3.name = @"hh";

55         p3.age = @"22";

56         

57         Person *p4 = [[Person alloc]init];

58         p4.name = @"hh";

59         p4.age = @"19";

60         NSMutableArray *sss = [NSMutableArray arrayWithObjects:p1,p2,p3,p4,nil];

61         NSSortDescriptor *sort1 = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES];

62         NSSortDescriptor *sort2 = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];

63         NSArray *s = @[sort1,sort2];

64         [sss sortUsingDescriptors:s];

65         NSLog(@"%@",sss);

person.h

1 #import <Foundation/Foundation.h>

2 

3 @interface Person : NSObject

4 @property (nonatomic,strong)NSString *name;

5 @property (nonatomic,strong)NSString *age;

6 @end

person.m

1 #import "Person.h"

2 

3 @implementation Person

4 - (NSString *)description

5 {

6     return [NSString stringWithFormat:@"%@ %@", _name,_age];

7 }

8 @end

运行结果分析：

2015-06-01 17:37:55.984 Array[2030:140148] ss

2015-06-01 17:37:55.985 Array[2030:140148] ddd

2015-06-01 17:37:55.985 Array[2030:140148] sad

2015-06-01 17:37:55.986 Array[2030:140148] ss

2015-06-01 17:37:55.986 Array[2030:140148] ddd

2015-06-01 17:37:55.986 Array[2030:140148] sad

2015-06-01 17:37:55.986 Array[2030:140148] ss

2015-06-01 17:37:55.986 Array[2030:140148] ss

2015-06-01 17:37:55.986 Array[2030:140148] ddd

2015-06-01 17:37:55.987 Array[2030:140148] ddd

2015-06-01 17:37:55.987 Array[2030:140148] sad

2015-06-01 17:37:55.987 Array[2030:140148] sad

2015-06-01 17:37:55.992 Array[2030:140148] ss

2015-06-01 17:37:55.992 Array[2030:140148] ddd

2015-06-01 17:37:55.992 Array[2030:140148] sad

2015-06-01 17:37:55.992 Array[2030:140148] sad

2015-06-01 17:37:55.992 Array[2030:140148] ddd

2015-06-01 17:37:55.993 Array[2030:140148] ss

2015-06-01 17:37:55.993 Array[2030:140148] (

    "dd 14",

    "hh 19",

    "hh 22",

    "ss 16"

)