ios – Swift嵌套过滤器优化？

我试图在 Swift中做一些使用KVC在Objective-C中很容易做到的事情.在iOS9中添加的新 Contacts framework在大多数情况下比 old AddressBook API更容易使用.但是通过其手机号码找到联系人似乎很难.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@L_801_5@所有联系人,然后使用NSPreDicate过滤KVC查询.结构是：

CNContact-> phonenumbers->(String,CNPhonenumber-> stringvalue)

在下面的代码中假定我通过以下方式@L_801_5@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？

let matches = contacts.filter {
    return $0.phonenumbers
                .flatMap { $0.value as? CNPhonenumber }
                .contains { $0.stringvalue == jennysPhone }
}