小编ray*_*ohn的帖子

所以我在Realm中有一个非常简单的Book模型

class Book: Object {

    dynamic var title: String!
    dynamic var author: String!
}

而我正试图在帮助类中检索我的所有书籍:

var userBookLibrary = [Book]()
let realm = try! Realm()    

func getBooksFromLocalDatastore() {
    userBookLibrary = realm.objects(Book)
}

这一行:

userBookLibrary = realm.objects(Book)

抛出标题中的错误.

我疯了,或者这是不是正是什么境界文件告诉我们做什么？

我无法异步从Alamofire请求中检索数据.

class BookGetter {

    static let instance = BookGetter()

    func getBook(bookId: String) -> Book {

        let rootUrl = "https://www.someusefulbookapi.com/bookid=?"
        let url = rootUrl + bookId
        var title = ""

        Alamofire.request(.GET, url).response { response in

            let jsonDict = JSON(data: response.2!)

            title = String(jsonDict["items"][0]["volumeInfo"]["title"])
        }
        let book = Book(title: title)
        print(book.title)
        return book
    }
}

输出print(book.title)是"",我明白这是因为print语句在请求返回之前运行.

如何book仅在使用请求中的数据实例化时才能返回实例？

let animal["legs"] = currentAnimal.legCount

let animal["canFly"] = currentAnimal.canFly

let animal["chicken"] = currentAnimal.isSoonToBeNugget

let anim....

其中之一是nil.我有大约10个这些并且想要将每个值打印到控制台而不必去

print(animal["legs"])
print(animal["canFly"])
print(animal["chicken"])
print(anim....)

最简洁的方法是什么？