试试这个：

let str = yourVar.takeRetainedValue() as String

let value : String? = ABMultiValueCopyValueAtIndex(multivalue, 0).takeRetainedValue() as? String

尝试使用此函数将Unmanaged转换为Stirng

func convertCfTypeToString(cfValue: Unmanaged<AnyObject>!) -> String?{

    let value = Unmanaged.fromOpaque(
        cfValue.toOpaque()).takeUnretainedValue() as CFString
    if CFGetTypeID(value) == CFStringGetTypeID(){
        return value as String
    } else {
        return nil
    }
}

用途：

let value = convertCfTypeToString(cfValue: ABMultiValueCopyValueAtIndex(multivalue, 0))

布尔

let obj = classType.perform(selector)
    if let obj = obj as? AnyObject {
        let pointer: UnsafeMutableRawPointer = Unmanaged<AnyObject>.passUnretained(obj).toOpaque()
        let valueBool: Bool = pointer.load(as: Bool.self)
        return valueBool
    }
    return false