ios - 为什么该方法要在最后运行？

Question

我正在尝试根据某些参数恢复所有动物对象。首先，我需要从解析中检索它们的位置以及名称，但由于我要导入多个并使用地理编码器，所以我使用的是字符串，而不是数组。因此，我不是将导入的信息附加到数组中，而是改变一个变量。我认为会发生的情况是，查询将遍历第一个对象，然后运行retrieveLocation方法，然后继续处理从解析导入的下一个对象，但它会导入所有内容，然后运行该方法，所以最后我只得到1个对象应该进口多少。

let query = PFQuery(className: "Animals")
    query.findObjectsInBackgroundWithBlock { (objects: [PFObject]?, error: NSError?) in
        if(error == nil){
            for object in objects!{
                        if let addressobj = object["Add"] as? NSDictionary{
                            if let address = addressobj["address"] as? String{

                                self.addr = address
                                print("sdfadsf \(self.addr)")

                            }
                        }
                        if let name = object["Name"] as? String{
                            self.impname = name
                            print("rturrty \(self.impname)")
                            self.retrieveLocation()
                        }
                 }
           }
      }
func retrieveLocation(){
    let geocoder = CLGeocoder()

        geocoder.geocodeAddressString(addr, completionHandler: {(placemarks, error) -> Void in
            if((error) != nil){
                print("Error", error)
            }
            if let placemark = placemarks?.first {
                let coordinates = PFGeoPoint(location: placemark.location)
                if(whatever is true){
                 append the name and address into an array. This is the part where I just get repeats of the LATEST  imported object.
              }
            }

        })

}

Answer 1

如果您使用局部变量并将该局部变量传递给以字符串作为参数的retrieveLocation的实现，这应该可以工作retrieveLocation(address: String)

let query = PFQuery(className: "Animals")
query.findObjectsInBackgroundWithBlock { (objects: [PFObject]?, error: NSError?) in
    if(error == nil){
      for object in objects!{
      if let addressobj = object["Add"] as? NSDictionary{
        if let address = addressobj["address"] as? String{

        let newAddress = address
        print("sdfadsf \(self.addr)")

        }
      }
   if let name = object["Name"] as? String{
     self.impname = name
     print("rturrty \(self.impname)")
     self.retrieveLocation(newAdress)
    }
  }
 }
}

func retrieveLocation(address: String){
    let geocoder = CLGeocoder()

    geocoder.geocodeAddressString(address, completionHandler: {(placemarks, error) -> Void in
        if((error) != nil){
            print("Error", error)
        }
        if let placemark = placemarks?.first {
            let coordinates = PFGeoPoint(location: placemark.location)
            if(whatever is true){
                append the name and address into an array. This is the part where I just get repeats of the LATEST  imported object.
            }
        }
    })
}

问题似乎是，当在 geocodeAdresString 方法中使用 self.addr 时，for 循环已完成，因此覆盖了在某个时刻单独保存的所有先前值self.addr。通过使用局部变量，每次执行时都会使用唯一的值来 geocodeAddressString