ios - Xcode Swift 2 变量声明(实例成员不能用于类型 View Controller )

Question

我正在开发一个项目，该项目使用用户在文本字段中定义的 IP 地址发送一些 HTTP 命令。 IP 地址基本上通过管道传输到我的应用程序的许多不同功能中。当我这样做时，我一直遇到“实例成员不能用于类型”错误。在变量声明的基础上，执行以下操作的正确方法是什么？我将收到大约 40-50 个不同的请求。

@IBOutlet weak var myIPaddress: UITextField!
var baserequest = "http://\(myIPaddress):8088/api/?function="
var requestA = "\(baserequest)myFunctionA&value=abc"
var requestB = "\(baserequest)myFunctionB&value=xyz"
var requestC = "\(baserequest)myFunctionC&value=123"
...
...

我不确定这是否重要，但因为我们使用的是 HTTP 命令，其中一个声明看起来像这样

var program1 = NSMutableURLRequest(URL: NSURL(string: "\(baseRequest)activeinput&input=1" )!)

* 更新 *

我不确定我的问题是什么。这是我的代码，它仍然会抛出该错误。在

var request1 = NSMutableURLRequest(URL: NSURL(string: "\(baserequest)activeinput&input=1" )!)

这是我的全部代码

import UIKit
import Foundation


func httpGet(request: NSURLRequest!, callback: (String?, NSError?) -> Void) {
let task = NSURLSession.sharedSession().dataTaskWithRequest(request) { data, response, error in
    guard error == nil && data != nil else {
        callback("", error)
        return
    }

    callback(String(data: data!, encoding: NSUTF8StringEncoding), nil)
}
task.resume()
}

class FirstViewController: UIViewController, UITextFieldDelegate {

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}



@IBOutlet weak var vmixip: UITextField!
var baserequest: String = ""

func textFieldDidEndEditing(textField: UITextField) {
    updateBaseRequest(textField.text!)
}

func updateBaseRequest(vmixip: String) {
    baserequest = "http://\(vmixip):8088/api/?function="
}

var request1 = NSMutableURLRequest(URL: NSURL(string: "\(baserequest)activeinput&input=1" )!)
@IBAction func Program1(sender: UIButton) {
    if let image = UIImage(named:"g1") {
        sender.setImage(image, forState: .Normal)
    }
    httpGet(request1) { string, error in
        guard error == nil && string != nil else {
            print(error?.localizedDescription)
            return
        }

        print(string!) //
    }


}

}

Answer 1

在获得用户的 IP 地址后，您应该在函数中初始化请求变量。该错误试图告诉您变量的默认值 can't something that hasn't been initialized yet (我的 IP 地址)。

类似于:

@IBAction func addressEntered(sender: UIButton) {
    // NOTE: Use myIPaddress.text to get the text
    baserequest = "http://\(myIPaddress.text):8088/api/?function="
    requestA = "\(baserequest)myFunctionA&value=abc"
    requestB = "\(baserequest)myFunctionB&value=xyz"
    requestC = "\(baserequest)myFunctionC&value=123"
}

此外，如果您在整个类(class)中都需要这些变量，则需要将它们声明为可选变量:

class MyClass {
    var requestA: String?
    ...
}

或者，您可以将请求变量转换为 computed properties :

class MyClass {
    var baseRequest: String?
    var requestA: String {
        // Beware, this would crash if used before baseRequest was initialized
        return "\(baseRequest!)myFunctionA&value=abc"
    }
}