授予联系人权限后，Tableview将不会重新加载

Question

我正在使用Swift 4.2和Xcode 10.2.1。

在出现并授予“联系人”权限请求后，我需要帮助重新加载表格视图。当前，对话框显示首次请求使用权限，但是在第一次使用期间获得许可后，不会重新加载表格视图。如果我关闭应用程序并重新打开，则联系人将按预期显示（换句话说，当未显示请求权限对话框时，它会显示正常）。这是我的代码：

在viewDidLoad的{​​{1}}中：

ContactsViewController

在 // Load the contacts from the phone ContactService.fetchContacts(completion: { (contacts) in if contacts != nil { self.deviceContacts = contacts! self.tableView.reloadData() } }) 中：

ContactService

我尝试在static func fetchContacts(completion: @escaping (_ contacts: [Contact]?) -> Void) { var deviceContacts:[Contact] = [Contact]() // Set up default storage for the contacts let store = CNContactStore() // Request access to the contacts if not already given. store.requestAccess(for: .contacts) { (granted, error) in if let error = error { print("Failed to request access:", error) completion (nil) } if granted { print("Access granted.") // Information to retrieve let keys = [CNContactIdentifierKey, CNContactGivenNameKey, CNContactFamilyNameKey, CNContactNicknameKey, CNContactNameSuffixKey, CNContactOrganizationNameKey, CNContactPhoneNumbersKey, CNContactImageDataAvailableKey, CNContactImageDataKey] let request = CNContactFetchRequest(keysToFetch: keys as [CNKeyDescriptor]) // Sort by last name request.sortOrder = CNContactSortOrder.familyName do { try store.enumerateContacts(with: request , usingBlock: { (contact, stopPointerifYouWantToStopEnumerating) in // Got the contacts from the device, now format as a Contact and put them into our array let formattedContact = Contact(contactDetails: contact, favoriteNumbers: [], opened: false) deviceContacts.append(formattedContact) }) } catch let error { print("Failed to enumerate contacts:", error) } } else { print ("Access denied.") completion (nil) } } completion(deviceContacts) } 的完成中将dispatchGroup.enter()和.leave()放在if granted和.notify内，但是没有用。

Answer 1

您需要更改completion的位置

try store.enumerateContacts(with: request
    , usingBlock: { (contact, stopPointerifYouWantToStopEnumerating) in

        // Got the contacts from the device, now format as a Contact and put them into our array
        let formattedContact = Contact(contactDetails: contact, favoriteNumbers: [], opened: false)
        deviceContacts.append(formattedContact)
})  
completion(deviceContacts)

目前应该从store.requestAccess(for: .contacts) { (granted, error) in 中检索联系人，而且这里不需要调度组，因为它是一个异步任务，数量不多

---

requestAccess的结果发生在后台线程中，因此请考虑

DispatchQueue.main.async { 
  self.tableView.reloadData()
}