iOS 内存泄露

Question

+ (NSMutableDictionary *)getKeychainQuery:(NSString *)service {
    return [NSMutableDictionary dictionaryWithObjectsAndKeys:
            (__bridge_transfer id)kSecClassGenericPassword,(__bridge_transfer id)kSecClass,
            service, (__bridge_transfer id)kSecAttrService,
            service, (__bridge_transfer id)kSecAttrAccount,
            (__bridge_transfer id)kSecAttrAccessibleAfterFirstUnlock,(__bridge_transfer id)kSecAttrAccessible,
            nil];
}为什么这段代码会造成内存泄露？该怎么改？

Answer 1

+ (NSMutableDictionary *)getKeychainQuery:(NSString *)service {
    return [NSMutableDictionary dictionaryWithObjectsAndKeys:
            (__bridge id)kSecClassGenericPassword,(__bridge id)kSecClass,
            service, (__bridge id)kSecAttrService,
            service, (__bridge id)kSecAttrAccount,
            (__bridge id)kSecAttrAccessibleAfterFirstUnlock,(__bridge id)kSecAttrAccessible,
            nil];
}

Answer 2

__bridge只改变对象的类型,并不会改变对象的所有权
__bridge_transfer在将对象转为oc对象的同时会把所有权也交给oc对象

Answer 3

右边Annotation 显示100.00% return [NSMutableDictionary dictionaryWithObjectsAndKeys: