1
NSArray *array = @[@"苹果", @"香蕉", @"橘子"];

1
NSMutableArray *mutableArray = [NSMutableArray array]; // 空数组
2
[mutableArray addObject:@"苹果"];                     // 添加一个元素
3
[mutableArray addObjectsFromArray:@[@"香蕉", @"橘子"]]; // 添加多个元素

1
NSString *fruit = [mutableArray objectAtIndex:1];  // 访问第2个元素
2
NSLog(@"第二个水果是：%@", fruit);
3

4
NSLog(@"数组元素总数：%lu", (unsigned long)[mutableArray count]);

1
for (NSString *item in mutableArray) {
2
    NSLog(@"%@", item);
3
}

1
[mutableArray replaceObjectAtIndex:0 withObject:@"西瓜"]; // 替换第一个元素

1
[mutableArray removeObjectAtIndex:1];     // 删除索引为1的元素
2
[mutableArray removeObject:@"西瓜"];       // 删除指定值（第一次出现的）
3
[mutableArray removeLastObject];          // 删除最后一个元素
4
[mutableArray removeAllObjects];          // 删除所有元素

1
#import <Foundation/Foundation.h>
2

3
int main(int argc, const char * argv[]) {
4
    @autoreleasepool {
5
        NSArray* array = [NSArray arrayWithObjects:@"LV", @"Burberry",@"BV",@"LR" ,@"miumiu",nil];
6
        NSLog(@"first:%@",[array objectAtIndex:1]);
7
        NSLog(@"last:%@",[array lastObject]);
8

9
        //截取索引2开始长度为1的数组
10
        NSArray* array1 = [array objectsAtIndexes:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(2, 1)]];
11
        NSLog(@"%@",array1);
12
        //查找对象在数组中的索引
13
        NSLog(@"miumiu: %ld", [array indexOfObject:@"miumiu"]);
14
        //在索引范围2，3中查找BV，结果是：
15
        NSLog(@"BV in(2,2) :%ld", [array indexOfObject:@"BV" inRange: NSMakeRange(2, 2)]);
16
        array = [array arrayByAddingObject:@"Mr.Dandy"];
17
        array = [array arrayByAddingObjectsFromArray:[NSArray arrayWithObjects:@"alo", @"an", nil]];
18
        for (int i = 0; i < array.count; i++) {
19
            NSLog(@"%@", [array objectAtIndex:i]);
20
        }
21
        //从索引2开始截取1个元素，得到新数组array2，只包含“BV”
22
        NSArray* array2 = [array subarrayWithRange:NSMakeRange(2, 1)];
23
        for (int i = 0; i < array2.count; i++) {
24
            NSLog(@"%@", [array2 objectAtIndex:i]);
25
        }
26
    }
27
    return 0;
28
}
29
#### 对几何元素的整体调用方法
30

31

32
笔者暂时还未理解，后续补全
33

34

35
#### 排序
36

37

38
> _sortedArrayUsingFunction:contes_:该方法使用排序函数对集合元素进行一个排序,该排序函数必须返回NSOrderedDesceding,NSOrderedAscending,NSOrderedSame三个枚举常量。 _sortedArrayUsingSelector:_该方法使用集合元素自身的方法对集合元素进行排序，它的排序函数同样会返回上面给出的三个枚举值。 _sortedArrayUsingComparator:_该方法使用代码块对与集合元素进行排序
39

40

41
三个方法的返回值都是一个排序好的NSArray对象。
42

43

44
```objective-c
45
NSInteger inSort (id num1, id num2, void* context) {
46
    int v1 = [num1 intValue];
47
    int v2 = [num2 intValue];
48
    if (v1 < v2) {
49
        return NSOrderedAscending;
50
    } else if (v1 == v2) {
51
        return NSOrderedSame;
52
    } else {
53
        return NSOrderedDescending;
54
    }
55
}
56
int main(int argc, const char * argv[]) {
57
    @autoreleasepool {
58
        NSArray* array1 = [NSArray arrayWithObjects:@"C++",@"Python",@"Perl",@"C",@"Objective-C",@"Ruby", nil];
59
        array1 = [array1 sortedArrayUsingSelector:@selector(compare:)];
60
        NSLog(@"%@", array1);
61
        NSArray* array2 = [NSArray arrayWithObjects:[NSNumber numberWithInt:20], [NSNumber numberWithInt:12], [NSNumber numberWithInt:-8],[NSNumber numberWithInt:50], [NSNumber numberWithInt:19],nil];
62
        array2 = [array2 sortedArrayUsingFunction:inSort context:nil];
63
        NSLog(@"%@", array2);
64
        NSArray* array3 = [array2 sortedArrayUsingComparator:^(id obj1, id obj2) {
65
            if ([obj1 intValue] > [obj2 intValue]) {
66
                return NSOrderedDescending;
67
            } else if ([obj1 intValue] < [obj2 intValue]) {
68
                return NSOrderedAscending;
69
            } else {
70
                return NSOrderedSame;
71
            }
72
        }];
73
        NSLog(@"%@", array3);
74
    }
75
    return 0;
76
}
77
#### 使用枚举器遍历元素
78

79

80
我们有两个方法获得枚举器
81

82

83
- objectEnumerator:正序遍历
84
- reverseObjectEnumerator:逆序遍历
85

86
枚举器的方法有以下两个
87

88

89
- allObjects:获取枚举集合中所有的元素
90
- reverseObjectEnumerator:获取被枚举集合中的下一个元素。
91

92

93
```objective-c
94
int main(int argc, const char * argv[]) {
95
    @autoreleasepool {
96
        NSArray* array1 = [NSArray arrayWithObjects:@"C++",@"Python",@"Perl",@"C",@"Objective-C",@"Ruby", nil];
97
        NSEnumerator* en = [array1 objectEnumerator];
98
        id object;
99
        while (object = [en nextObject]) {
100
            NSLog(@"%@", object);
101
        }
102
        NSLog(@"");
103
        NSEnumerator* an = [array1 reverseObjectEnumerator];
104
        while (object = [an nextObject]) {
105
            NSLog(@"%@", object);
106
        }
107

108
    }
109
    return 0;
110
}

1
for(type variableName in collection) {
2
  //variableName自动迭代访问每一个元素
3
}

1
int main(int argc, const char * argv[]) {
2
    @autoreleasepool {
3
        NSArray* array1 = [NSArray arrayWithObjects:@"C++",@"Python",@"Perl",@"C",@"Objective-C",@"Ruby", nil];
4
        for (id object in array1) {
5
            NSLog(@"%@", object);
6
        }
7

8
    }
9
    return 0;
10
}

1
#import <Foundation/Foundation.h>
2

3
int main(int argc, const char * argv[]) {
4
    @autoreleasepool {
5
        NSArray* initArray = [[NSArray alloc] initWithObjects:@"BV",@"Barbour",@"miumiu", nil];
6
        NSLog(@"initArray: %@", initArray);
7
        NSArray* initArray2 = [NSArray arrayWithObjects:@"BV",@"Barbour",@"miomio", nil];
8
        NSArray* initArray3 = @[@"BV",@"On",@"Lulu"];
9
        NSArray* initArray4 = [[NSArray alloc] initWithArray:initArray2];
10
        NSLog(@"initArray2: %@", initArray2);
11
        NSLog(@"initArray3: %@", initArray3);
12
        NSLog(@"initArray4: %@", initArray4);
13

14
        NSInteger count = [initArray4 count];
15
        NSLog(@"%ld",(long)count);
16

17
        NSString* str = [initArray objectAtIndex:1];  //从零开始，所以是第二个
18
        NSLog(@"%@", str);
19
        NSLog(@"%@", initArray[1]);
20

21
        BOOL flag = [initArray containsObject:@"BV"];
22
        NSLog(@"%d", flag);
23

24
        for (NSString* name in initArray) {
25
            NSLog(@"%@", name);
26
        }
27
        for (int i = 0; i < initArray.count; i++) {
28
            NSLog(@"%@", initArray[i]);
29
        }
30

31
        // 空数组
32
        NSMutableArray* mutableArray = [NSMutableArray array];
33
        NSMutableArray* mutableArray2 = [[NSMutableArray alloc] init];
34
        NSArray* origin = @[@"A", @"B"];
35
        NSMutableArray* mutableArray3 = [NSMutableArray arrayWithArray:origin];
36

37
        [mutableArray insertObject:@"Burberry" atIndex:0];
38
        NSLog(@"mutableArray:%@", mutableArray);
39
        [mutableArray addObject:@"ecco"];
40
        NSLog(@"mutableArray:%@", mutableArray);
41

42
        NSMutableArray* mutableArray4 = [@[@"a", @"b",@"c", @"d"]mutableCopy];
43
        NSLog(@"mutableArray4:%@", mutableArray4);
44

45
        [mutableArray4 replaceObjectAtIndex:3 withObject:@"dd"];
46
        NSLog(@"mutableArray4:%@", mutableArray4);
47

48
        [mutableArray4 removeObject:@"c"];
49
        NSLog(@"mutableArray4:%@", mutableArray4);
50

51
        [mutableArray4 removeObjectAtIndex:2];
52
        NSLog(@"mutableArray4:%@", mutableArray4);
53

54

55
    }
56
    return 0;
57
}

1
int main(int argc, const char * argv[]) {
2
    @autoreleasepool {
3
        NSCountedSet* set1 = [NSCountedSet setWithObjects:@"iOS讲义",@"Android",@"Java", nil];
4
        [set1 addObject:@"Java"];
5
        [set1 addObject:@"Java"];
6
        NSLog(@"%@", NSCollectionToString(set1));
7
        NSLog(@"Java的添加次数为%ld", [set1 countForObject:@"Java"]);
8
        [set1 removeObject:@"Java"];
9
        NSLog(@"%@", NSCollectionToString(set1));
10
        NSLog(@"Java的添加次数为%ld", [set1 countForObject:@"Java"]);
11
        [set1 removeObject:@"Java"];
12
        [set1 removeObject:@"Java"];
13
        NSLog(@"%@", NSCollectionToString(set1));
14
        NSLog(@"Java的添加次数为%ld", [set1 countForObject:@"Java"]);
15
    }
16
    return 0;
17
}
18
### 有序集合
19

20

21
NSOrderedSet最主要的点在于可以保持与安素的添加顺序，而且每一个元素都有缩影，可以根据缩影来操作元素。
22

23

24
```objective-c
25
int main(int argc, const char * argv[]) {
26
    @autoreleasepool {
27
        NSOrderedSet* set = [NSOrderedSet orderedSetWithObjects:[NSNumber numberWithInt:40],[NSNumber numberWithInt:12],[NSNumber numberWithInt:-9],[NSNumber numberWithInt:20], nil];
28
        NSLog(@"first :%@", [set firstObject]);
29
        NSLog(@"last:%@", [set lastObject]);
30
        NSLog(@"索引为2的元素:%@", [set objectAtIndex:2]);
31
        NSIndexSet* indexSet = [set indexesOfObjectsPassingTest:^(id obj, NSUInteger idx, BOOL* stop) {
32
            return (BOOL)([obj intValue] > 10); // 返回大于10的值
33
        }];
34
        NSLog(@"%@", indexSet);
35
    }
36
    return 0;
37
}

1
[mdict setObject:@"西邮" forKey:@"university"];

1
NSSet* initSet = [[NSSet alloc] initWithObjects:@"a",@"b",@"c", nil];
2
        NSLog(@"%@", initSet);
3

4
        NSSet* initSet2 = [NSSet setWithObjects:@"a",@"b",@"c", nil];
5
        NSLog(@"%@", initSet2);
6

7
        NSString* str = [initSet2 anyObject];
8
        NSLog(@"%@", str);
9

10
NSMutableSet *mInitSet = [[NSMutableSet alloc]initWithCapacity:2];
11

12
            //添加 (再次添加后输出时还是只有一个，但是不会报错)
13
            [mInitSet addObject:@"xiaohong"];
14
            NSLog(@"mInitSet = %@",mInitSet);
15
            //重复添加是无效的，但是不会报错
16
            [mInitSet addObject:@"xiaohuang"];
17
            NSLog(@"mInitSet = %@",mInitSet);
18

19
            //删除
20
            [mInitSet removeObject:@"xiaohong"];
21
            NSLog(@"mInitSet = %@",mInitSet);
22

23
            //删除所有
24
            [mInitSet removeAllObjects];
25
            NSLog(@"mInitSet = %@",mInitSet);