【iOS】NSArray/NSMutableArray创建,获取,遍历,排序

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1 数组基本

1.1 创建数组

NSArray 是不可变数组,一旦创建完成就不能够对数组进行,添加,删除等操作

下面这种方式相当于什么都没做

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NSArray * array = [[NSArray alloc] init];

NSLog(@"%@",array);

1.2 通过构造方法的方式创建一个NSArray

在创建一个NSArray的时候,集合的最后一个元素一定是nil

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NSArray * array1 = [NSArray arrayWithObjects:@"one",@"two",@"three", nil];
NSLog(@"%@",array1);

1.3 数组中可以存储不同类型的对象

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NSNumber * number = [NSNumber numberWithInt:10];
NSArray * array2 = [[NSArray alloc] initWithObjects:@"one",@"two",number, nil];
NSLog(@"array2  %@",array2);

1.4 数组实际上存储的是对象的地址,同样也可以存储数组的地址

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NSArray * a1 = [[NSArray alloc] initWithObjects:@"one",@"two",@"three", nil];
NSArray * a2 = [[NSArray alloc] initWithObjects:@"1",@"2",@"3", nil];
NSArray * a3 = [[NSArray alloc] initWithObjects:a1,a2, nil];

NSLog(@"a3 %@",a3);

1.5 存储自定义的对象

最好都 description 方法

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@interface Person : NSObject

@property (nonatomic,strong)NSString * name;
@property (nonatomic,assign)int age;

- (id)initWithName:(NSString *)name andAge:(int)age;

@end
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@implementation Person

- (id)initWithName:(NSString *)name andAge:(int)age
{
    if (self = [super init])
    {
        _name = name;
        _age = age;
    }
    return self;
}

- (NSString *)description
{
    return [NSString stringWithFormat:@"age = %d name = %@",_age,_name];
}

@end
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Person * p1 = [[Person alloc] initWithName:@"xiaozhe" andAge:20];
Person * p2 = [[Person alloc] initWithName:@"hell" andAge:18];
Person * p3 = [[Person alloc] initWithName:@"marray" andAge:38];

NSArray * array3 = [[NSArray alloc] initWithObjects:p1,p2,p3, nil];
NSLog(@"array3  %@",array3);

1.6 数组中存储基本数据类型

如果你要在数组中存储基本数据类型,请包装好了之后在去存 NSNumber

注意不要把nil值存储到 NSArray 中,会导致数据丢失

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NSString * str = nil;
NSArray * array4 = [[NSArray alloc] initWithObjects:@"2",str,[NSNumber numberWithInt:23], nil];
NSLog(@"array4 %@",array4);

1.7 创建数组的快捷方式

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NSArray * karray = @[@"a",@"b",@"c"];
NSLog(@"karray %@",karray);

1.8 快速获得一个数组中的元素

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NSString * kstr = karray[0];
NSLog(@"kstr %@",kstr);

1.9 从数组中取出数据

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NSArray * array = [[NSArray alloc] initWithObjects:@"one",@"two",@"three", nil];

数组的index时从0开始的

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NSString * str = [array objectAtIndex:0];
NSLog(@"str %@",str);

1.10 获得数组的元素个数

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NSUInteger arrayCount = [array count];
NSLog(@"arrayCount %d",arrayCount);

1.11 判断数组中是否存在某个对象

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Person * p1 = [[Person alloc] initWithName:@"yofer" andAge:20];
Person * p2 = [[Person alloc] initWithName:@"luke" andAge:30];

NSArray * array = @[p1,p2];

BOOL isContain = [array containsObject:p1];
if (isContain)
{
    NSLog(@"存在");
}else
{
    NSLog(@"不存在");
}

2 遍历数组

2.1 使用for循环遍历数组

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NSArray * array = @[@"one",@"two",@"three"];
for (int i = 0; i < array.count; i++)
{
    NSString * str = array[i];
    NSLog(@"array[%d] = %@",i,str);
}

2.2 使用增强for循环的方式遍历数组

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for (NSString * str in array)
{
    NSLog(@"str = %@",str);
}

2.3 注意事项

如果你的数组中村粗了多种不同类型的数据,那么最好不要调用某个对象特有的方法,会导致程序崩溃

在实际的开发中,一个数组往往只负责存储一种数据类型

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Person * p1 = [[Person alloc] init];
NSArray * array2 = @[@"one",[NSNumber numberWithInt:10],p1];

for (NSString * str in array2)
{
//    NSLog(@"array2 str %@",str);
//    NSLog(@"str %ld",str.length);
}

2.4 枚举器

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NSArray * array3 = @[@"one",@"two",@"three"];

NSEnumerator * enumerateor =  [array3 objectEnumerator];

NSString * value;

while (value = [enumerateor nextObject]) {
    NSLog(@"enum str %@",value);
}

3 数组排序

3.1 使用 sortedArrayUsingSelector

是最简单的排序方式

数组是按照你存入元素的顺序存储的

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NSArray * array = @[@"b",@"d",@"a",@"z"];
NSLog(@"排序前 array %@",array);

array = [array sortedArrayUsingSelector:@selector(compare:)];
// NSArray * array1 = [array sortedArrayUsingSelector:@selector(compare:)];
NSLog(@"排序后 array %@",array);

3.2 使用block方式排序

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NSArray * array2 = @[@"z",@"4",@"b",@"3",@"x"];

NSLog(@"array2 排序前 %@",array2);
array2 = [array2 sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
    
    /*
    NSComparisonResult retuslt = [obj1 compare:obj2];
    
    return retuslt;
     */
    //obj1 compare obj2 就是正序排序
    //  return [obj1 compare:obj2];
    //obj2 compare obj1 就是倒序排序
    return [obj2 compare:obj1];
    
}];
NSLog(@"array2 排序后 %@",array2);

先给一个 Person 类

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@interface Person : NSObject

@property (nonatomic,assign) int age;
@property (nonatomic,strong) NSString * name;
@property (nonatomic,strong) NSString * year;

- (id)initWithName:(NSString *)name  andAge:(int)age andYear:(NSString *)year;
//+ (id)personWithName:(NSString *)name  andAge:(int)age andYear:(NSString *)year;

@end
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@implementation Person

- (id)initWithName:(NSString *)name  andAge:(int)age andYear:(NSString *)year
{
    if (self = [super init])
    {
        _name = name;
        _age = age;
        _year = year;
        
    }
    return self;
}

- (NSString *)description
{
    return [NSString stringWithFormat:@"name %@ age %d year %@",_name,_age,_year];
}

@end

3.3 定制化数组对象排序

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Person * p1 = [[Person alloc] initWithName:@"xiaozhe" andAge:20 andYear:@"1990"];
Person * p2 = [[Person alloc] initWithName:@"alex" andAge:18 andYear:@"2990"];
Person * p3 = [[Person alloc] initWithName:@"merry" andAge:25 andYear:@"1890"];

NSArray * array3 = @[p1,p2,p3];
NSLog(@"array3 排序前 %@",array3);

如果你向给你自己定义的对象排序,必须根据某一个属性来排序,

sortDescriptorWithKey 参数要的就是你对象中,要依据哪个属性来排序,你就把哪个属性的名字当成key传入

ascending YES表示正序 NO表示倒序

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NSSortDescriptor * d1 = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:NO];
NSSortDescriptor * d2 = [NSSortDescriptor sortDescriptorWithKey:@"year" ascending:NO];

如果你要使用多个属性进行排序,默认在前面的NSSortDescriptor优先级比较高

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NSArray * descripts = @[d2,d1];

array3 = [array3 sortedArrayUsingDescriptors:descripts];

NSLog(@"array 3 排序后  %@",array3);

结果：

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2016-08-14 14:13:57.238 05-数组排序[2105:516991] array3 排序前 (
    "name xiaozhe age 20 year 1990",
    "name alex age 18 year 2990",
    "name merry age 25 year 1890"
)
2016-08-14 14:13:57.238 05-数组排序[2105:516991] array 3 排序后  (
    "name alex age 18 year 2990",
    "name xiaozhe age 20 year 1990",
    "name merry age 25 year 1890"
)

再次测试：

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NSArray * array4 = @[p1,p2,p3];
NSLog(@"array4 排序前 %@",array4);
array4 = [array4 sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
    
    Person * p1 = obj1;
    Person * p2 = obj2;
    
    //year
    return [p1.year compare:p2.year];
}];
NSLog(@"array4 排序后 %@",array4);

结果：

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2016-08-14 14:13:57.238 05-数组排序[2105:516991] array4 排序前 (
    "name xiaozhe age 20 year 1990",
    "name alex age 18 year 2990",
    "name merry age 25 year 1890"
)
2016-08-14 14:13:57.238 05-数组排序[2105:516991] array4 排序后 (
    "name merry age 25 year 1890",
    "name xiaozhe age 20 year 1990",
    "name alex age 18 year 2990"
)

4 可变数组: NSMutableArray

NSMutableArray 继承至 NSArray

4.1 创建可变数组

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NSMutableArray * array = [[NSMutableArray alloc] initWithCapacity:0];

使用addObject 动态给数组中增加元素

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[array addObject:@"one"];
[array addObject:@"two"];
[array addObject:@"three"];
[array addObject:@"one"];

NSString * str1 = @"one";
NSString * str2 = @"two";
NSString * str3 = @"three";

数组中可以存储,同一个对象多次

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[array addObject:str1];
[array addObject:str2];
[array addObject:str3];
[array addObject:str1];

4.2 指定对象插入的位置

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[array insertObject:str1 atIndex:2];

4.3 删除 会通过对象,删除数组中所有的同一个地址的对象

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[array removeObject:str1];

4.4 通过索引的方式删除对象,超出了数组的count值,那么就会导致异常 index beyond bounds

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[array removeObjectAtIndex:0];

[array addObject:str2];
[array addObject:str3];
[array addObject:str1];

4.5 删除数组中所有的元素

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[array removeAllObjects];

NSLog(@"array %@",array);

[array addObject:str2];
[array addObject:str3];
[array addObject:str1];

5 可变数组 NSMutableArray 遍历

5.1 for换遍历

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for (int i = 0; i < array.count; i++)
{
    NSString * str = [array objectAtIndex:i];
    
    //在遍历数组的时候,千万不要给数组中,增加,或者删除元素
    // [array removeObject:str1];
    
    NSLog(@"str %@",str);
  
}

5.2 增强for循环

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for (NSString * str in array)
{
//    [array removeObject:str1];
    //如果你在增强for循环中,删除元素,会直接导致异常出现
    NSLog(@"str %@",str);
}

5.3 枚举器

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NSEnumerator * enumerator = [array objectEnumerator];
NSString * value;
while (value = [enumerator nextObject]) {
    //如果你在枚举器中,删除元素,会直接导致异常出现
//    [array removeObject:str1];
    NSLog(@"str %@",value);
}

5.4 要通过遍历的方式确定删除哪个元素怎么办

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NSMutableArray * array2 = [[NSMutableArray alloc] init];
[array2 addObject:@"1"];
[array2 addObject:@"2"];
[array2 addObject:@"3"];
[array2 addObject:@"4"];
[array2 addObject:@"5"];

NSMutableArray * tmp = [[NSMutableArray alloc] init];

for (NSString * str in array2)
{
    if ([str isEqualToString:@"3"])
    {
        [tmp addObject:str];
    }
}

NSLog(@"array2 %@",array2);
NSLog(@"tmp %@",tmp);

结果：

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2016-08-14 14:35:20.437 06-可变数组[2252:538261] array2 (
    1,
    2,
    3,
    4,
    5
)
2016-08-14 14:35:20.437 06-可变数组[2252:538261] tmp (
    3
)

遍历临时数组

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for (int i = 0; i < tmp.count; i++)
{
    NSString * str = [tmp objectAtIndex:i];
    
    //从原数组中删除,临时数组中存储的对象
    [array2 removeObject:str];
}

NSLog(@"array2 %@",array2);

新博客文章地址：NSArray/NSMutableArray创建,获取,遍历,排序
CSDN文章地址：NSArray/NSMutableArray创建,获取,遍历,排序