NSArrayNSMutableArray创建,获取,遍历,排序 - iOS

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

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

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

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

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

@interface Person : NSObject @property (nonatomic,strong)NSString * name; @property (nonatomic,assign)int age; - (id)initWithName:(NSString *)name andAge:(int)age; @end @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 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

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

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

1.8 快速获得一个数组中的元素

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

1.9 从数组中取出数据

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

数组的index时从0开始的

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

1.10 获得数组的元素个数

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

1.11 判断数组中是否存在某个对象

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

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

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

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

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

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

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

@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 @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

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

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

NSArray * descripts = @[d2,d1]; array3 = [array3 sortedArrayUsingDescriptors:descripts]; NSLog(@"array 3 排序后 %@",array3);

结果：

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：

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：

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

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

使用addObject 动态给数组中增加元素

[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

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

4.2 指定对象插入的位置

[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

[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

[array removeObjectAtIndex:0]; [array addObject:str2]; [array addObject:str3]; [array addObject:str1];

4.5 删除数组中所有的元素

[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

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

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

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

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：

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

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