[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"
)