Swift

Question

我在中心点 (class) 工作，请求和检索我的数据。

这个class可以从任何视图调用：

override func viewDidLoad() {
    super.viewDidLoad()

    let group = dispatch_group_create()
    var data = RestApiManager(group)
    dispatch_group_notify(group, dispatch_get_main_queue()) {
        return data
    }
}

class RestApiManager {

    let user = "user"
    let password = "password"

    var result: JSON = []

    init(group) {

        dispatch_group_enter(group)
        Alamofire.request(.GET, "http://example.com/api/")
            .authenticate(user: user, password: password)
            .responseJSON { _, _, result in
                switch result {
                case .Success(let data):
                    self.result[] = JSON(data)
                case .Failure(_, let error):
                    print("Request failed with error: \(error)")
                }
                dispatch_group_leave(group)
        }
    }
}

但是初始化class时已经失败了。

谁能帮我设计一个合适的方法？？

谢谢和问候

Answer 1

import XCPlayground

XCPlaygroundPage.currentPage.needsIndefiniteExecution = true

import Foundation

class C {
    var txt: String = "start"
    init(group: dispatch_group_t) {
        dispatch_group_enter(group)
        print(txt)
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) { () -> Void in
            usleep(200000)
            self.txt = "end"
            print(self.txt)
            dispatch_group_leave(group)
        }
    }
}

func f() {
    let group = dispatch_group_create()
    let c = C(group: group)
    dispatch_group_notify(group, dispatch_get_main_queue()) { () -> Void in
        print("notify: \(c) created")
    }
}

f()
print("continue running ...")

这对我来说没有任何问题。你写了 "But it already fails when initializing the class." 这到底是什么意思？详细解释你的 'failure' ... 顺便说一下，我不明白你如何从组通知处理程序中 return 你的数据（return 数据）...（通常来自任何异步代码）

Swift - Grand Central Dispatch Class

Swift - Grand Central Dispatch Class

asynchronous

request

grand-central-dispatch

alamofire