Swift嵌套过滤器优化？

Question

我试图在Swift中做一些使用KVC在Objective-C中很容易做到的事情.iOS9中添加的新Contacts框架在大多数情况下比旧的AddressBook API更容易使用.但通过手机号码找到联系人似乎很困难.提供查找联系人的谓词仅限于名称和唯一标识符.在Objective-C中,您可以获取所有联系人,然后使用NSPredicate过滤KVC查询.结构是:

CNContact-> phoneNumbers - >(String,CNPhoneNumber-> stringValue)

在下面的代码中假设我通过以下方式获取了联系人:

let keys = [CNContactEmailAddressesKey,CNContactPhoneNumbersKey, CNContactFormatter.descriptorForRequiredKeysForStyle(.FullName)]
let fetchRequest = CNContactFetchRequest(keysToFetch: keys)
var contacts:[CNContact] = []
try! CNContactStore().enumerateContactsWithFetchRequest(fetchRequest) { ...

我想将stringValue与已知值进行比较.这是我到目前为止在游乐场所拥有的:

import UIKit
import Contacts

let JennysPhone    = "111-867-5309"
let SomeOtherPhone = "111-111-2222"
let AndAThirdPhone = "111-222-5309"

let contact1 = CNMutableContact()
contact1.givenName = "Jenny"
let phone1 = CNPhoneNumber(stringValue: JennysPhone)
let phoneLabeled1 = CNLabeledValue(label: CNLabelPhoneNumberMobile, value: phone1)
contact1.phoneNumbers.append(phoneLabeled1)

let contact2 = CNMutableContact()
contact2.givenName = "Billy"
let phone2 = CNPhoneNumber(stringValue: SomeOtherPhone)
let phoneLabeled2 = CNLabeledValue(label: CNLabelPhoneNumberMobile, value: phone2)
contact2.phoneNumbers.append(phoneLabeled2)

let contact3 = CNMutableContact()
contact3.givenName = "Jimmy"
let phone3 = CNPhoneNumber(stringValue: SomeOtherPhone)
let phoneLabeled3 = CNLabeledValue(label: CNLabelPhoneNumberMobile, value: phone3)
contact3.phoneNumbers.append(phoneLabeled3)

let contacts = [contact1, contact2, contact3]

let matches = contacts.filter { (contact) -> Bool in
    let phoneMatches = contact.phoneNumbers.filter({ (labeledValue) -> Bool in
        if let v = labeledValue.value as? CNPhoneNumber
        {
            return v.stringValue == JennysPhone
        }
        return false
    })
    return phoneMatches.count > 0
}

if let jennysNum = matches.first?.givenName
{
    print("I think I found Jenny:  \(jennysNum)")
}
else
{
    print("I could not find Jenny")
}

这确实有效,但效率不高.在设备上,我需要在后台线程中运行它,如果此人有很多联系人,可能需要一段时间.有没有更好的方法使用新的iOS Contacts框架通过电话号码(或电子邮件地址,相同的想法)找到联系人？

Answer 1

如果您正在寻找更快捷的方式:

let matches = contacts.filter {
    return $0.phoneNumbers
                .flatMap { $0.value as? CNPhoneNumber }
                .contains { $0.stringValue == JennysPhone }
}

.flatMap将每个成员phoneNumbers从类型转换CNLabeledValue为类型CNPhoneNumber,忽略那些无法转换的成员.

.contains 检查这些电话号码是否与Jenny的号码相符.