Objective-C 中的自动引用计数无法防止或最小化哪些类型的泄漏

Objective-C 中的自动引用计数（Automatic Reference Counting，简称 ARC）是一种内存管理技术，用于自动管理对象的内存分配和释放。它通过计算对象的引用计数来确定何时释放对象，并且在不再需要对象时自动将其释放，从而减少内存泄漏的风险。然而，ARC 并不能完全消除所有类型的内存泄漏，下面将介绍一些 ARC 无法防止或最小化的泄漏类型。

objective-c
@interface Person : NSObject
@property (nonatomic, strong) NSString *name;
@property (nonatomic, strong) Person *bestFriend;
@end
@implementation Person
@end
Person *person1 = [[Person alloc] init];
person1.name = @"Alice";
Person *person2 = [[Person alloc] init];
person2.name = @"Bob";
person1.bestFriend = person2;
person2.bestFriend = person1;

objective-c
@property (nonatomic, weak) Person *bestFriend;

objective-c
typedef void (^CompletionBlock)(void);
@interface NetworkManager : NSObject
@property (nonatomic, copy) CompletionBlock completionBlock;
@end
@implementation NetworkManager
- (void)startRequest {
    self.completionBlock = ^{
        NSLog(@"%@", self); // 引用了 self
    };
    
    self.completionBlock();
}
@end
NetworkManager *manager = [[NetworkManager alloc] init];
[manager startRequest];

objective-c
__weak typeof(self) weakSelf = self;
self.completionBlock = ^{
    NSLog(@"%@", weakSelf); // 使用弱引用
};

objective-c
CFStringRef cfString = CFStringCreateWithCString(NULL, "Hello", kCFStringEncodingUTF8);
NSString *string = (__bridge NSString *)cfString; // 将 CFStringRef 转换为 NSString
// 忘记释放 cfString