ABMultiValue地址簿多值属性在Swift中编译错误答案

【问题标题】：ABMultiValue address book multi-value properties compile error in SwiftABMultiValue地址簿多值属性在Swift中编译错误
【发布时间】：2015-03-23 20:07:29
【问题描述】：

代码在 Objective-C 中工作，试图转换为 Swift。我在第 10 行提供了有效的 Objective-C 代码和给出编译错误的 Swift 代码（for subValue in aPropertyValue ... 快速枚举器。Swift 错误“类型‘ABMultiValue’不符合协议‘SequenceType’”。

一些ABPerson 属性可能包含多个值（例如多个电话号码）并且是ABMultiValue 类的对象（尽管Xcode 调试器将它们报告为ABMultiValueCoreDataWrapper 类）。附加的 Objective-C 代码循环遍历多个值。我试图在 Swift 中做同样的事情，但无法克服编译错误。两者都是 Xcode 命令行项目。

Objective-C 代码：

#import <Foundation/Foundation.h>
#import <AddressBook/AddressBook.h>
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        ABAddressBook *addressBook = [ABAddressBook sharedAddressBook];
        NSArray *people = [addressBook people];
        for (ABPerson *person in people) {
            for (NSString *aProperty in [ABPerson properties]) {
                id aPropertyValue = [person valueForProperty: aProperty];
                if ([aPropertyValue isKindOfClass: [ABMultiValue class]]) {
                    for (id subValue in aPropertyValue) {
                        NSLog(@"%@",subValue);
                    }
                }
            }
        }
    }
    return 0;
}

快速代码：

import Foundation
import AddressBook
let addressBook = ABAddressBook.sharedAddressBook()
let people = addressBook.people()
for person in people {
    for property in ABPerson.properties() {
        if let aPropertyValue : AnyObject = person.valueForProperty(property as NSString) {
            if aPropertyValue is ABMultiValue {
//                for subValue in aPropertyValue {
                for subValue in aPropertyValue as ABMultiValue {
                    println("\(subValue)") 
                }
            }
        }
    }
}

【问题讨论】：

标签： macos swift abaddressbook

【解决方案1】：

你显然可以使用索引：

let addressBook = ABAddressBook.sharedAddressBook()
let people = addressBook.people()
for person in people {
    for property in ABPerson.properties() {
        if let multiValue = person.valueForProperty(property as NSString) as? ABMultiValue {
            for i in 0 ..< multiValue.count() {
                println(multiValue.valueAtIndex(i))
            }
        }
    }
}

或者，按照this answer 中的建议，您可以定义符合SequenceType 的扩展：

extension ABMultiValue: SequenceType {
    public func generate() -> NSFastGenerator {
        return NSFastGenerator(self)
    }
}

那么你可以：

let addressBook = ABAddressBook.sharedAddressBook()
let people = addressBook.people()
for person in people {
    for property in ABPerson.properties() {
        if let multiValue = person.valueForProperty(property as NSString) as? ABMultiValue {
            for identifier in multiValue {
                let value: AnyObject = multiValue.valueForIdentifier(identifier as String)
                println("\(identifier) : \(value)")
            }
        }
    }
}

【讨论】：