15.Object－C－－NSArray数组的排序

NSArray数组的排序有三种方式：

1、简单排序（sortedArrayUsingSelector:）

2、利用block语法（sortedArrayUsingComparator:）

3、高级排序（sortedArrayUsingDescriptors:）

1、简单排序（sortedArrayUsingSelector:）

如果只是对字符串的排序，可以利用sortedArrayUsingSelector:方法就可以了，代码如下：

 1 #pragma mark 数组排序 sortedArrayUsingSelector
 2
 3 void arraySort1()
 4 {
 5     NSArray *array = [NSArray arrayWithObjects:@"6",@"9",@"1",@"2",nil];
 6     //返回一个排好序的数组，原来的数组不会变 （SEL）中传递的是排序的规则。@selector(compare:)
 7     //制定元素的比较方法 compare
 8     NSArray *arrayNew = [array sortedArrayUsingSelector:@selector(compare:)];
 9     NSLog(@"arrayNew :%@",arrayNew);
10 }

这里是制定使用Compare方法进行排序。我们也可以制定自己的排序方法

 1 #import <Foundation/Foundation.h>
 2 @class Book;
 3 @interface Student : NSObject
 4 @property(nonatomic,retain)NSString *firstName;
 5 @property(nonatomic,retain)NSString *lastName;
 6 @property(nonatomic,retain)Book *book;
 7 //快速创建student
 8 + (id)studentWithFirstName:(NSString*)firstName lastName:(NSString*)lastName;
 9 //比较规则
10 - (NSComparisonResult)compareStudent:(Student*)stu;
11 @end
12
13 #import "Student.h"
14 #import "Book.h"
15 @implementation Student
16 + (id)studentWithFirstName:(NSString*)firstName lastName:(NSString*)lastName
17 {
18     //类方法自动释放所以使用autorelease
19     Student *stu = [[[Student alloc]init]autorelease];
20     stu.firstName = firstName;
21     stu.lastName = lastName;
22     return stu;
23 }
24
25 - (NSComparisonResult)compareStudent:(Student*)stu
26 {
27     //1.先按照姓排序
28     NSComparisonResult result = [self.lastName compare:stu.lastName];
29
30     if(result == NSOrderedSame)
31     {
32         result = [self.firstName compare:stu.firstName];
33     }
34     return result;
35 }
36 - (NSString *)description
37 {
38     return  [NSString stringWithFormat:@"[%@ %@]",self.lastName,self.firstName];
39 }
40
41 - (void)dealloc
42 {
43     [_book release];
44     [_firstName release];
45     [_lastName release];
46     [super dealloc];
47 }
48 @end
49
50
51 #pragma mark 数组排序 arraySort2
52 void arraySort2()
53 {
54     Student *stu = [Student studentWithFirstName:@"QY" lastName:@"Ma"];
55     Student *stu1 = [Student studentWithFirstName:@"jf" lastName:@"Jia"];
56     Student *stu2 = [Student studentWithFirstName:@"sy" lastName:@"Qu"];
57     NSArray *array = [NSArray arrayWithObjects:stu,stu1,stu2,nil];
58     //指定排序的方法
59     NSArray *arrayNew = [array sortedArrayUsingSelector:@selector(compareStudent:)];
60     NSLog(@"arrayNew : %@",arrayNew);
61
62 }

2.利用block语法（sortedArrayUsingComparator:）

这是苹果官方提供的block方法，其中数组排序可以用sortedArrayUsingComparator:方法

 1 void arraySort3()
 2 {
 3     Student *stu = [Student studentWithFirstName:@"QY" lastName:@"Ma"];
 4     Student *stu1 = [Student studentWithFirstName:@"jf" lastName:@"Jia"];
 5     Student *stu2 = [Student studentWithFirstName:@"sy" lastName:@"Qu"];
 6     NSArray *array = [NSArray arrayWithObjects:stu,stu1,stu2,nil];
 7     //利用block进行排序
 8     NSArray *arrayNew =   [array sortedArrayUsingComparator:^NSComparisonResult(Student *obj1, Student *obj2) {
 9         //1.先按照姓排序
10         NSComparisonResult result = [obj1.lastName compare:obj2.lastName];
11
12         if(result == NSOrderedSame)
13         {
14             result = [obj1.firstName compare:obj2.firstName];
15         }
16         return result;
17     }];
18     NSLog(@"arrayNew : %@",arrayNew);
19 }

3.高级排序（sortedArrayUsingDescriptors:）

如果是这样一种情况呢？Student类里有另外一个类的变量，比如说Student类除了lastName，firstName变量，还有一本书，Book类里有个name属性。对Student对象进行排序，有这样的要求：按照Book的name排序，如果是同一本书，那么再按照lastName进行排序，如果lastName也相同，最后按照firstName进行排序。

代码如下：

  1 //Book
  2 #import <Foundation/Foundation.h>
  3
  4 @interface Book : NSObject
  5 @property(nonatomic,retain)NSString *name;
  6 + (id)bookWithName:(NSString*)name;
  7 @end
  8
  9 #import "Book.h"
 10
 11 @implementation Book
 12 + (id)bookWithName:(NSString*)name
 13 {
 14     Book *book = [[[Book alloc]init]autorelease];
 15     book.name = name;
 16     return book;
 17
 18
 19 }
 20 - (void)dealloc
 21 {
 22     [_name release];
 23     [super dealloc];
 24 }
 25 @end
 26
 27 //Student
 28 #import <Foundation/Foundation.h>
 29 @class Book;
 30 @interface Student : NSObject
 31 @property(nonatomic,retain)NSString *firstName;
 32 @property(nonatomic,retain)NSString *lastName;
 33 @property(nonatomic,retain)Book *book;
 34 //快速创建student
 35 + (id)studentWithFirstName:(NSString*)firstName lastName:(NSString*)lastName;
 36 //快速创建student
 37 + (id)studentWithFirstName:(NSString*)firstName lastName:(NSString*)lastName bookName:(NSString*)bookName;
 38 //比较规则
 39 - (NSComparisonResult)compareStudent:(Student*)stu;
 40 @end
 41
 42 #import "Student.h"
 43 #import "Book.h"
 44 @implementation Student
 45 + (id)studentWithFirstName:(NSString*)firstName lastName:(NSString*)lastName
 46 {
 47     //类方法自动释放所以使用autorelease
 48     Student *stu = [[[Student alloc]init]autorelease];
 49     stu.firstName = firstName;
 50     stu.lastName = lastName;
 51     return stu;
 52 }
 53
 54
 55 //快速创建student
 56 + (id)studentWithFirstName:(NSString*)firstName lastName:(NSString*)lastName bookName:(NSString*)bookName
 57 {
 58     Student *stu = [Student studentWithFirstName:firstName lastName:lastName];
 59     stu.book = [Book bookWithName:bookName];
 60     return stu;
 61
 62 }
 63 - (NSComparisonResult)compareStudent:(Student*)stu
 64 {
 65     //1.先按照姓排序
 66     NSComparisonResult result = [self.lastName compare:stu.lastName];
 67
 68     if(result == NSOrderedSame)
 69     {
 70         result = [self.firstName compare:stu.firstName];
 71     }
 72     return result;
 73 }
 74 - (NSString *)description
 75 {
 76     return  [NSString stringWithFormat:@"[%@ %@ %@]",self.lastName,self.firstName,self.book.name];
 77 }
 78
 79 - (void)dealloc
 80 {
 81     [_book release];
 82     [_firstName release];
 83     [_lastName release];
 84     [super dealloc];
 85 }
 86 @end
 87
 88 //将排序描述按照顺序存入到数组中
 89 #pragma mark 数组排序 sortedArrayUsingDescriptors 排序描述器
 90 void arraySort5()
 91 {
 92     Student *stu1 = [Student studentWithFirstName:@"QY" lastName:@"Ma" bookName:@"book3"];
 93     Student *stu2 = [Student studentWithFirstName:@"JF" lastName:@"Jia" bookName:@"book1"];
 94     Student *stu3 = [Student studentWithFirstName:@"SY" lastName:@"Qu" bookName:@"book4"];
 95     NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, nil];
 96     //放入到描述器里面
 97     NSSortDescriptor *bookNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"book.name" ascending:YES];
 98     NSSortDescriptor *lastNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"lastName" ascending:YES];
 99     NSSortDescriptor *firstName = [NSSortDescriptor sortDescriptorWithKey:@"firstName" ascending:YES];
100     NSArray *array1 = [NSArray arrayWithObjects:bookNameDesc,lastNameDesc,firstName,nil];
101     NSArray *arrayNew = [array sortedArrayUsingDescriptors:array1];
102     NSLog(@"arrayNew :%@",arrayNew);
103
104 }