ios - 在 Swift 3 中请求访问联系人

Question

我想访问用户的通讯录，并计划使用 Apple 提供的通讯录和 ContactsUI 框架。

不过，首先，我需要获得访问用户联系人的权限，但在这样做时遇到了问题。在 Swift 2 中，可以像这样请求许可:

func requestForAccess(completionHandler: (accessGranted: Bool) -> Void) {
    let authorizationStatus = CNContactStore.authorizationStatusForEntityType(CNEntityType.Contacts)

    switch authorizationStatus {
    case .Authorized:
        completionHandler(accessGranted: true)

    case .Denied, .NotDetermined:
        self.contactStore.requestAccessForEntityType(CNEntityType.Contacts, completionHandler: { (access, accessError) -> Void in
            if access {
                completionHandler(accessGranted: access)
            }
            else {
                if authorizationStatus == CNAuthorizationStatus.Denied {
                    dispatch_async(dispatch_get_main_queue(), { () -> Void in 
                        let message = "\(accessError!.localizedDescription)\n\nPlease allow the app to access your contacts through the Settings."
                        self.showMessage(message)
                    })
                }
            }
        })

    default:
        completionHandler(accessGranted: false)
    }
}

我尝试像这样将它转换为 Swift 3，但我仍然遇到错误。错误是“实例成员‘async’不能用于‘DispatchQueue’类型；您是想使用这种类型的值吗？”:

func requestForAccess(completionHandler: @escaping (_ accessGranted: Bool) -> Void) {
    let authorizationStatus = CNContactStore.authorizationStatus(for: CNEntityType.contacts)

    switch authorizationStatus {
    case .authorized:
        completionHandler(true)

    case .denied, .notDetermined:
        self.contactStore.requestAccess(for: CNEntityType.contacts, completionHandler: { (access, accessError) -> Void in
            if access {
                completionHandler(access)
            }
            else {
                if authorizationStatus == CNAuthorizationStatus.denied {
                    DispatchQueue.async(group: DispatchQueue.main, execute: { () -> Void in //error here
                        let message = "\(accessError!.localizedDescription)\n\nPlease allow the app to access your contacts through the Settings."
                        self.showMessage(message)
                    })
                }
            }
        })

    default:
        completionHandler(false)
    }
}

谁能帮忙解决这个问题？任何帮助将不胜感激。提前致谢。

干杯，西奥

Answer 1

代替

DispatchQueue.async(group: DispatchQueue.main, execute: { ... }

做

DispatchQueue.main.async { ... }

---

顺便说一句，如果权限之前已被拒绝，则无需再次请求授权，因为操作系统不会向最终用户显示任何“授予访问权限”的用户界面。只有当用户之前没有拒绝访问时，它才会这样做。

如果访问通讯录对于应用程序的成功运行确实必不可少，您可以向他们显示一个提醒，让他们可以选择直接从您的应用程序转到“设置”:

func requestAccess(completionHandler: @escaping (_ accessGranted: Bool) -> Void) {
    switch CNContactStore.authorizationStatus(for: .contacts) {
    case .authorized:
        completionHandler(true)
    case .denied:
        showSettingsAlert(completionHandler)
    case .restricted, .notDetermined:
        store.requestAccess(for: .contacts) { granted, error in
            if granted {
                completionHandler(true)
            } else {
                DispatchQueue.main.async {
                    self.showSettingsAlert(completionHandler)
                }
            }
        }
    }
}

private func showSettingsAlert(_ completionHandler: @escaping (_ accessGranted: Bool) -> Void) {
    let alert = UIAlertController(title: nil, message: "This app requires access to Contacts to proceed. Go to Settings to grant access.", preferredStyle: .alert)
    if
        let settings = URL(string: UIApplication.openSettingsURLString),
        UIApplication.shared.canOpenURL(settings) { 
            alert.addAction(UIAlertAction(title: "Open Settings", style: .default) { action in
                completionHandler(false)
                UIApplication.shared.open(settings)
            })
    }
    alert.addAction(UIAlertAction(title: "Cancel", style: .cancel) { action in
        completionHandler(false)
    })
    present(alert, animated: true)
}