NSArray的三种排序方法

1.sortedArrayUsingSelector

（按Key值大小对NSDictionary排序）

1 NSMutableArray *array = [NSMutableArray arrayWithObjects:
2                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj0", [NSNumber numberWithInt:0], nil],
3                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj5", [NSNumber numberWithInt:5], nil],
4                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj2", [NSNumber numberWithInt:2], nil],
5                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj3", [NSNumber numberWithInt:3], nil],
6                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj1", [NSNumber numberWithInt:1], nil],
7                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj4", [NSNumber numberWithInt:4], nil], nil];
8     
9 NSArray *resultArray = [array sortedArrayUsingSelector:@selector(compare:)];

因为NSDictionary没有compare的排序比较方法，所以需要我们自己写

 1 .h
 2 @interface NSDictionary (compare)
 3 {}
 4 
 5 -(NSComparisonResult)compare:(NSDictionary *)otherDictionary;
 6 
 7 @end
 8 
 9 .m
10 @implementation NSDictionary (compare)
11 
12 - (NSComparisonResult)compare: (NSDictionary *)otherDictionary
13 {
14     NSDictionary *tempDictionary = (NSDictionary *)self;
15     
16     NSNumber *number1 = [[tempDictionary allKeys] objectAtIndex:0];
17     NSNumber *number2 = [[otherDictionary allKeys] objectAtIndex:0];
18     
19     NSComparisonResult result = [number1 compare:number2];
20     
21     return result == NSOrderedDescending; // 升序
22 //    return result == NSOrderedAscending;  // 降序
23 }
24 
25 @end

2.sortedArrayUsingComparator

 1     NSMutableArray *array = [NSMutableArray arrayWithObjects:
 2                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj0", [NSNumber numberWithInt:0], nil],
 3                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj5", [NSNumber numberWithInt:5], nil],
 4                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj2", [NSNumber numberWithInt:2], nil],
 5                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj3", [NSNumber numberWithInt:3], nil],
 6                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj1", [NSNumber numberWithInt:1], nil],
 7                              [NSDictionary dictionaryWithObjectsAndKeys:@"Obj4", [NSNumber numberWithInt:4], nil], nil];
 8     
 9 //    NSArray *resultArray = [array sortedArrayUsingSelector:@selector(compare:)];
10     
11     NSArray *resultArray = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
12         
13         NSNumber *number1 = [[obj1 allKeys] objectAtIndex:0];
14         NSNumber *number2 = [[obj2 allKeys] objectAtIndex:0];
15         
16         NSComparisonResult result = [number1 compare:number2];
17         
18         return result == NSOrderedDescending; // 升序
19 //        return result == NSOrderedAscending;  // 降序
20     }];

3.sortedArrayUsingDescriptors & sortUsingDescriptors

前者带返回值，是NSArray的方法，排好序的数组是返回值中的数组；

后者不带返回值，是NSMutableArray的方法，是对当前数组自己排序

 1 .h
 2 @interface Person : NSObject
 3 {
 4     NSString  *_name;
 5     
 6     NSInteger  _age;
 7 }
 8 @property (nonatomic, retain) NSString  *name;
 9 @property (nonatomic, assign) NSInteger  age;
10 @end
11 
12 .m
13 @implementation Person
14 @synthesize name = _name;
15 @synthesize age  = _age;
16 
17 
18 - (void)dealloc
19 {
20     [_name release];
21     
22     [super dealloc];
23 }
24 
25 @end

 1     Person *person1 = [[Person alloc] init];
 2     [person1 setName:@"ABC"];
 3     [person1 setAge:24];
 4     
 5     Person *person2 = [[Person alloc] init];
 6     [person2 setName:@"ACB"];
 7     [person2 setAge:22];
 8     
 9     Person *person3 = [[Person alloc] init];
10     [person3 setName:@"ABD"];
11     [person3 setAge:33];
12     
13     NSMutableArray *array = [NSMutableArray arrayWithObjects:person1, person2, person3, nil];
14     [person1 release];
15     [person2 release];
16     [person3 release];
17     
18     NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"_age" ascending:YES];
19     
20     NSArray *tempArray = [array sortedArrayUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
21     
22     for(NSInteger i = 0; i < [tempArray count]; i++)
23     {
24         NSLog(@"%@--------%d
", [[tempArray objectAtIndex:i] name], [[tempArray objectAtIndex:i] age]);
25     }
26     
27 //    [array sortUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
28 //    
29 //    for(NSInteger i = 0; i < [array count]; i++)
30 //    {
31 //        NSLog(@"%@--------%d
", [[array objectAtIndex:i] name], [[array objectAtIndex:i] age]);
32 //    }

sortDescriptorWithKey:@"_age",以age作为标准来做比较。

 1     Person *person1 = [[Person alloc] init];
 2     [person1 setName:@"ABCD"];
 3     [person1 setAge:24];
 4     
 5     Person *person2 = [[Person alloc] init];
 6     [person2 setName:@"ACBD"];
 7     [person2 setAge:22];
 8     
 9     Person *person3 = [[Person alloc] init];
10     [person3 setName:@"ABDC"];
11     [person3 setAge:33];
12     
13     Person *person4 = [[Person alloc] init];
14     [person4 setName:@"ACDB"];
15     [person4 setAge:22];
16     
17     NSMutableArray *array = [NSMutableArray arrayWithObjects:person1, person3, person4, person2, nil];
18     [person1 release];
19     [person2 release];
20     [person3 release];
21     [person4 release];
22     
23     NSSortDescriptor *sortDescriptor1 = [NSSortDescriptor sortDescriptorWithKey:@"_age" ascending:YES];
24     NSSortDescriptor *sortDescriptor2 = [NSSortDescriptor sortDescriptorWithKey:@"_name" ascending:YES];
25     
26     NSArray *tempArray = [array sortedArrayUsingDescriptors:[NSArray arrayWithObjects:sortDescriptor1, sortDescriptor2, nil]];
27     
28     for(NSInteger i = 0; i < [tempArray count]; i++)
29     {
30         NSLog(@"%@--------%d
", [[tempArray objectAtIndex:i] name], [[tempArray objectAtIndex:i] age]);
31     }
32     
33 //    [array sortUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
34 //    
35 //    for(NSInteger i = 0; i < [array count]; i++)
36 //    {
37 //        NSLog(@"%@--------%d
", [[array objectAtIndex:i] name], [[array objectAtIndex:i] age]);
38 //    }

　　NSSortDescriptor *sortDescriptor1 = [NSSortDescriptorsortDescriptorWithKey:@"_age"ascending:YES];

　　NSSortDescriptor *sortDescriptor2 = [NSSortDescriptorsortDescriptorWithKey:@"_name"ascending:YES];

　　NSArray *tempArray = [array sortedArrayUsingDescriptors:[NSArrayarrayWithObjects:sortDescriptor1, sortDescriptor2, nil]];

这里的NSArray中的第一元素表示首先按照这个元素的升序或者降序进行排序,对于有重复项的，再按照第二元素进行排序，依次进行类推