Question

我正在使用以下代码访问ABAddressBook：

+ (void)connectToAddressBook {
    if(!_addressBook)
    {
        CFErrorRef error;
        _addressBook = ABAddressBookCreateWithOptions(NULL, &error);
        NSLog(@"Address book %@", _addressBook);

        if (error != nil) {
            NSLog(@"ERROR WHILE ACCESSING ADDRESS BOOK: %@", CFBridgingRelease(error));
            CFRelease(error);
        }

        if (ABAddressBookGetAuthorizationStatus() == kABAuthorizationStatusNotDetermined) {
            ABAddressBookRequestAccessWithCompletion(_addressBook, ^(bool granted, CFErrorRef error) {
                _isAccessToContactsAllowed = granted;
            });
        }
        else if (ABAddressBookGetAuthorizationStatus() == kABAuthorizationStatusAuthorized) {
            _isAccessToContactsAllowed = YES;
        }
        else {
            _isAccessToContactsAllowed = NO;
        }
    }
}

地址簿打开正常，但由于某种原因错误不是nil并记录当前类的名称：

ERROR WHILE ACCESSING ADDRESS BOOK: MyContactManager

为什么错误不是零？我的代码有点错吗？如果出现真正的错误，如何检测并停止尝试访问地址簿？

Answer 1

感谢来自Ilesh的反馈，这是我的固定方法：

+ (void)connectToAddressBook {
    if(!_addressBook) {
        CFErrorRef *error = nil;
        _addressBook = ABAddressBookCreateWithOptions(NULL, error);

        // To test if error is not nil:
        //error = CFErrorCreate(NULL, CFSTR("Hello, world."), 111, NULL);

        if (error != nil) {
            NSLog(@"ERROR WHILE ACCESSING ADDRESS BOOK: %@", CFBridgingRelease(error));
            CFRelease(error);
        }
        else {
            if (ABAddressBookGetAuthorizationStatus() == kABAuthorizationStatusNotDetermined) {
                ABAddressBookRequestAccessWithCompletion(_addressBook, ^(bool granted, CFErrorRef error) {
                    _isAccessToContactsAllowed = granted;
                });
            }
            else if (ABAddressBookGetAuthorizationStatus() == kABAuthorizationStatusAuthorized) {
                _isAccessToContactsAllowed = YES;
            }
            else {
                _isAccessToContactsAllowed = NO;
            }
        }
    }
}

修改

看来我最初的错误是没有将错误分配给 nil 。地址簿创建不会设置错误除非确实存在错误。所以我的未分配变量指向内存中的一些随机位置，这就是我第一次尝试时出现随机错误的原因。

更重要的是，如果出现错误，ABAddressBookCreateWithOptions将返回 nil ，因此正确的方法是：

if(_addressBook) { // do something } else { // there is an error }

Answer 2

将您的整个代码替换为此

+ (void)connectToAddressBook {
    if(!_addressBook)
    {
_addressBook = ABAddressBookCreateWithOptions(NULL, NULL);
    if (ABAddressBookGetAuthorizationStatus() == kABAuthorizationStatusNotDetermined) {
        ABAddressBookRequestAccessWithCompletion(addressBook,
                                                 ^(bool granted, CFErrorRef error) {
                                                     if (granted)
                                                      dispatch_async(dispatch_get_main_queue(), ^{
                                                        _isAccessToContactsAllowed = granted; 
                                                     });

                                                         });


    }
    else if (ABAddressBookGetAuthorizationStatus() == kABAuthorizationStatusAuthorized) {
        dispatch_async(dispatch_get_main_queue(), ^{
_isAccessToContactsAllowed = YES;

    });
    }
    else {
        UIAlertView *alert=[[UIAlertView alloc] initWithTitle:Nil message:@"You don't have permission of access contacts for access go to Setting-" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
    }
}}

访问ABAddressBook时出错

2 个答案: