[oc学习笔记]数组的遍历和排序（转）

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);

1 #import <Foundation/Foundation.h> 
2 
3 @interface Person : NSObject 
4 @property (nonatomic,strong)NSString *name; 
5 @property (nonatomic,strong)NSString *age; 
6 @end

1 #import "Person.h" 
2 
3 @implementation Person 
4 - (NSString *)description 
5 { 
6 return [NSString stringWithFormat:@"%@ %@", _name,_age]; 
7 } 
8 @end