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利用KVC的方式更方便地获取数组中对象的属性的最值平均值等

直接上代码 输出结果也在相应的代码里标注出来了

 1 //main.m文件
 2 #import <Foundation/Foundation.h>
 3 #import "Student.h"
 4 
 5 int main(int argc, const char * argv[]) {
 6     @autoreleasepool {
 7         
 8         NSMutableArray <Student *> *_studentArrM;
 9         NSMutableArray <Student *> *_studentArrMTest;
10         
11         _studentArrM = [NSMutableArray array];
12         _studentArrMTest = [NSMutableArray array];
13         
14         Student *s1 = [Student studentWithNum:001 chinese:90.0 math:96.0 english:100.0];
15         Student *s2 = [Student studentWithNum:002 chinese:90.0 math:100.0 english:96.0];
16         Student *s3 = [Student studentWithNum:003 chinese:100.0 math:90.0 english:96.0];
17         
18         [_studentArrM addObject:s1];
19         [_studentArrM addObject:s2];
20         [_studentArrM addObject:s3];
21         
22         double mathAvg = [[_studentArrM valueForKeyPath:@"@avg.math"]doubleValue];
23         double mathMax = [[_studentArrM valueForKeyPath:@"@max.math"]doubleValue];
24         double mathMin = [[_studentArrM valueForKeyPath:@"@min.math"]doubleValue];
25         double mathSum = [[_studentArrM valueForKeyPath:@"@sum.math"]doubleValue];
26         NSLog(@"数学平均分%f 数学最高分%f 数学最低分%f 所有人的数学总分%f",mathAvg,mathMax,mathMin,mathSum);
27         
28         /*
29          输出的内容为:数学平均分95.333333 数学最高分100.000000 数学最低分90.000000 所有人的数学总分286.000000
30          
31          提示:有兴趣的话可以自己多测试几组数据
32          */
33         
34         //接下来试着处理一下数组中的对象的是否有重复的问题
35         //测试需要我们可以再次给可变数组添加一个重复的对象
36         [_studentArrM addObject:s2];
37         [_studentArrM addObject:s2];
38         
39         NSArray *arrDistinct = [_studentArrM valueForKeyPath:@"@distinctUnionOfObjects.num"];
40         NSArray *arrUnion = [_studentArrM valueForKeyPath:@"@unionOfObjects.num"];
41         
42         NSLog(@"DistinctArray %@ \n UnionArray %@",arrDistinct,arrUnion);
43         /*
44          输出的内容为:
45          DistinctArray (
46          3,
47          2,
48          1
49          )//提示:没有重复的所有值
50          UnionArray (
51          1,
52          2,
53          3,
54          2,
55          2
56          )//提示:有重复的所有值
57          */
58         
59         //为了处理 多个数组 中的重复值的情况再次添加一个一个对象到测试数组
60         [_studentArrMTest addObject:s2];
61         
62         NSLog(@"%@",[@[_studentArrM,_studentArrMTest] valueForKeyPath:@"@distinctUnionOfArrays.num"]);
63         NSLog(@"%@",[@[_studentArrM,_studentArrMTest] valueForKeyPath:@"@unionOfArrays.num"]);
64         /*
65          输出的内容为
66          (3,
67          2,
68          1
69          )//提示:没有重复的所有值
70          
71          (1,
72          2,
73          3,
74          2,
75          2,
76          2
77          )//提示:有重复的所有值
78          
79          */
80     }
81     return 0;
82 }

 

//Student.h文件
#import
<Foundation/Foundation.h> @interface Student : NSObject /** 学号 */ @property (nonatomic,assign)int num; /** 语文成绩 */ @property (nonatomic,assign)double chinese; /** 语文成绩 */ @property (nonatomic,assign)double math; /** 语文成绩 */ @property (nonatomic,assign)double english; - (instancetype)initWithNum:(int)num chinese:(double)chinese math:(double)math english:(double)english; + (instancetype)studentWithNum:(int)num chinese:(double)chinese math:(double)math english:(double)english;

1
//Student.m文件 2 #import "Student.h" 3 4 @implementation Student 5 6 - (instancetype)initWithNum:(int)num chinese:(double)chinese math:(double)math english:(double)english{ 7 8 self = [super init]; 9 if(self){ 10 _num = num; 11 _chinese = chinese; 12 _math = math; 13 _english = english; 14 } 15 return self; 16 17 18 19 } 20 21 22 + (instancetype)studentWithNum:(int)num chinese:(double)chinese math:(double)math english:(double)english{ 23 24 return [[Student alloc]initWithNum:num chinese:chinese math:math english:english]; 25 26 } 27 28 @end

 

 

利用KVC的方式更方便地获取数组中对象的属性的最值平均值等