NSHashTable
类似NSSet 、 NSMutableSet，与其区别在于NSSet 、 NSMutableSet是对其成员的强类型引用，NSHashTable可以在创建时设置其对存储对象的持有方式。
特点
-
NSHashTable是无序的 -
NSHashTable是可变的 -
NSHashTable可以持有weak类型的成员变量 -
NSHashTable可以在添加成员变量的时候复制成员 -
NSHashTable可以随意的存储指针并且利用指针的唯一性来进行hash同一性检查（检查成员变量是否有重复）和对比操作（equal）
示例
@interface ViewController ()
@property (nonatomic, strong)NSHashTable *hashTable;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
self.view.backgroundColor = [UIColor whiteColor];
[self hashTableTest];
}
- (void)hashTableTest {
self.hashTable = [NSHashTable hashTableWithOptions:NSPointerFunctionsWeakMemory];
NSObject *obj1 = [[NSObject alloc] init];
NSObject *obj2 = [[NSObject alloc] init];
NSObject *obj3 = [[NSObject alloc] init];
NSObject *obj4 = [[NSObject alloc] init];
NSObject *obj5 = obj4;
[self.hashTable addObject:obj1];
[self.hashTable addObject:obj2];
[self.hashTable addObject:obj3];
[self.hashTable addObject:obj4];
[self.hashTable addObject:obj5];
[self.hashTable addObject:obj1];
NSLog(@"Members: %@", [self.hashTable allObjects]);
UIButton *btn1 = [UIButton buttonWithType:UIButtonTypeCustom];
btn1.backgroundColor = [UIColor redColor];
btn1.frame = CGRectMake(100, 100, 100, 100);
[btn1 addTarget:self action:@selector(btn1Click) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:btn1];
}
- (void)btn1Click {
NSLog(@"Members: %@", [self.hashTable allObjects]);
}
@end
结果：
Members: (
"",
"",
"",
""
)
Members: (
)
NSMapTable
类似NSDictionary 、NSMutableDictionary，区别于NSDictionary 、 NSMutableDictionary会复制keys并且通过强引用values来实现存储，NSMapTable可以在创建时设置其对存储对象的持有方式。
特点
-
NSMapTable是可变的。 -
NSMapTable可以通过弱引用来持有keys和values，所以当key或者value被deallocated的时候，所存储的实体也会被移除。 -
NSMapTable可以在添加value的时候对value进行复制 - 和
NSHashTable类似，NSMapTable可以随意的存储指针，并且利用指针的唯一性来进行对比和重复检查。
示例
- (void)mapTableTest {
self.mapTable = [[NSMapTable alloc] initWithKeyOptions:NSPointerFunctionsCopyIn valueOptions:NSPointerFunctionsWeakMemory capacity:10];
NSObject *obj1 = [[NSObject alloc] init];
NSObject *obj2 = [[NSObject alloc] init];
NSObject *obj3 = [[NSObject alloc] init];
NSObject *obj4 = [[NSObject alloc] init];
NSObject *obj5 = obj4;
[self.mapTable setObject:obj1 forKey:@"obj1"];
[self.mapTable setObject:obj2 forKey:@"obj2"];
[self.mapTable setObject:obj3 forKey:@"obj3"];
[self.mapTable setObject:obj4 forKey:@"obj4"];
[self.mapTable setObject:obj5 forKey:@"obj5"];
NSLog(@"Members: %@", self.mapTable);
UIButton *btn2 = [UIButton buttonWithType:UIButtonTypeCustom];
btn2.backgroundColor = [UIColor redColor];
btn2.frame = CGRectMake(100, 100, 100, 100);
[btn2 addTarget:self action:@selector(btn2Click) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:btn2];
}
- (void)btn2Click {
NSLog(@"Members: %@", self.mapTable);
}
结果
Members: NSMapTable {
[7] obj5 ->
[9] obj2 ->
[11] obj4 ->
[12] obj3 ->
[13] obj1 ->
}
Members: NSMapTable {
}
NSPointerArray
类似于数组的集合，但具有更广泛的可用内存语义；继承自NSObject。
特点
- 与
NSMutableArray一样，使用下标有序的插入或移除元素，且可修改数组内容； - 可以插入或删除
nil，并且nil参与count的计算； -
count可以set，如果直接set count，那么会使用nil占位； - 可以使用
weak来修饰成员； - 成员可以是所有指针类型；
- 遵循
NSFastEnumeration，可以通过for...in来进行遍历。
示例
- (void)pointerArrayTest {
self.pointerArray = [[NSPointerArray alloc] initWithOptions:NSPointerFunctionsWeakMemory];
NSObject *obj1 = [[NSObject alloc] init];
NSObject *obj2 = [[NSObject alloc] init];
NSObject *obj3 = [[NSObject alloc] init];
NSObject *obj4 = [[NSObject alloc] init];
NSObject *obj5 = obj4;
[self.pointerArray insertPointer:(__bridge void * _Nullable)obj1 atIndex:0];
[self.pointerArray insertPointer:(__bridge void * _Nullable)obj2 atIndex:1];
[self.pointerArray insertPointer:(__bridge void * _Nullable)obj3 atIndex:2];
[self.pointerArray insertPointer:(__bridge void * _Nullable)obj4 atIndex:3];
[self.pointerArray insertPointer:(__bridge void * _Nullable)obj5 atIndex:4];
NSLog(@"Members: %@", [self.pointerArray allObjects]);
for (NSObject *objc in self.pointerArray) {
NSLog(@"Member: %@", objc);
}
self.pointerArray.count = 10;
NSLog(@"Members: %@", [self.pointerArray allObjects]);
for (NSObject *objc in self.pointerArray) {
NSLog(@"Member: %@", objc);
}
UIButton *btn3 = [UIButton buttonWithType:UIButtonTypeCustom];
btn3.backgroundColor = [UIColor redColor];
btn3.frame = CGRectMake(100, 100, 100, 100);
[btn3 addTarget:self action:@selector(btn3Click) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:btn3];
}
- (void)btn3Click {
NSLog(@"Members: %@", [self.pointerArray allObjects]);
for (NSObject *objc in self.pointerArray) {
NSLog(@"Member: %@", objc);
}
}
结果：
Members: (
"",
"",
"",
"",
""
)
Member:
Member:
Member:
Member:
Member:
Members: (
"",
"",
"",
"",
""
)
Member:
Member:
Member:
Member:
Member:
Member: (null)
Member: (null)
Member: (null)
Member: (null)
Member: (null)
Members: (
)
Member: (null)
Member: (null)
Member: (null)
Member: (null)
Member: (null)
Member: (null)
Member: (null)
Member: (null)
Member: (null)
Member: (null)