ios - 当我将其放入viewDidLoad中时，为什么我的for循环没有完成？

Question

为什么我将函数的主体放入应该执行7次的for循环中，为什​​么函数的主体仅执行一次？

我的代码行如下

 override func viewDidLoad() {
            super.viewDidLoad()
            getLocationFromGeoCoding()
        }
    func getLocationFromGeoCoding() {
        for index in 0...6{
         geoCoder.reverseGeocodeLocation(sevenWorldWonderOb[index].location ?? CLLocation()) {[weak self] (placemarks, err) in
        if let err = err {
            print("Error",err.localizedDescription)
            return
        }else {
            guard let placemark = placemarks?.first else {return}
             let streetNumber = placemark.subThoroughfare
             let street = placemark.thoroughfare
             let city = placemark.locality
             let state = placemark.administrativeArea
            let country = placemark.country
            let Address = "\(streetNumber == nil ? "" : streetNumber!) \(street == nil ? "" : street!) \(city == nil ? "" : city!) \(state == nil ? "" : state!) \(country == nil ? "" : country!)"
            self?.addressLocation.append(Address)
            self?.wonderAddress.text = self?.addressLocation[index]
            }
        }

    }
}

Answer 1

异步工作时可以使用DispatchGroup。 reverseGeocodeLocation异步工作。如果您想知道何时在阵列中拥有所有地址

func getLocationFromGeoCoding() {
let group = DispatchGroup()
        for index in 0...6{
         group.enter()
         geoCoder.reverseGeocodeLocation(sevenWorldWonderOb[index].location ?? CLLocation()) {[weak self] (placemarks, err) in
            defer {
               group.leave()
           }
        if let err = err {
            print("Error",err.localizedDescription)

        } else {
            guard let placemark = placemarks?.first else { return}
             let streetNumber = placemark.subThoroughfare
             let street = placemark.thoroughfare
             let city = placemark.locality
             let state = placemark.administrativeArea
            let country = placemark.country
            let Address = "\(streetNumber == nil ? "" : streetNumber!) \(street == nil ? "" : street!) \(city == nil ? "" : city!) \(state == nil ? "" : state!) \(country == nil ? "" : country!)"
            self?.addressLocation.append(Address)
            self?.wonderAddress.text = self?.addressLocation[index]
            }


group.notify(queue: .main, execute: { // executed after all async calls in for loop finish
    print(“Got all addresses”)
    // do whatever you want to do on getting all addresse
})

    }

经过操场测试