首先我们来了解一下NSHashTable
NSHashTable效仿了NSSet(NSMutableSet),但提供了比NSSet更多的操作选项,尤其是在对弱引用关系的支持上,NSHashTable在对象/内存处理时更加的灵活。相较于NSSet,NSHashTable具有以下特性:
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self testWeakMemory];
}
把要观察的对象加入到HashTable中
- (void)testWeakMemory {
if (!_hashTablele) {
_hashTablele = [NSHashTable weakObjectsHashTable];
}
_obj = [[NSObject alloc] init];
[_hashTablele addObject:_obj];
NSLog(@"hashTablele: %@", _hashTablele);
}
HashTable中判断该对象是否存在,如果不存在就被释放了
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
self.obj = nil;
if ([_hashTablele containsObject:_obj]) {
NSLog(@"obj 对象没有被释放");
}
else{
NSLog(@"obj 对象已经被释放了");
}
NSLog(@"hashTablele: %@", _hashTablele);
}