swift中do catch的范围-无法为外部变量赋值
我已经编写了一些代码,对放置在服务器上的php脚本发出POST请求。我已经测试过了,那部分工作正常。我从服务器返回结果时遇到了问题-我以JSON格式获取结果,并在内部do catch语句中打印-没问题。我将返回变量赋值给在do catch之外声明的变量,该变量不“可见”。让我展示我的代码,当您看到代码时,解释会更简单:swift中do catch的范围-无法为外部变量赋值,swift,scope,swift2,nsjsonserialization,do-catch,Swift,Scope,Swift2,Nsjsonserialization,Do Catch,我已经编写了一些代码,对放置在服务器上的php脚本发出POST请求。我已经测试过了,那部分工作正常。我从服务器返回结果时遇到了问题-我以JSON格式获取结果,并在内部do catch语句中打印-没问题。我将返回变量赋值给在do catch之外声明的变量,该变量不“可见”。让我展示我的代码,当您看到代码时,解释会更简单: //sending inputs to server and receiving info from server let json:[String:AnyObject]
//sending inputs to server and receiving info from server
let json:[String:AnyObject] = [ "username" : username!, "password" : password!, "iphone" : "1" ]
var link = "http://www.pnc.hr/rfid/login.php"
var novi:String = ""
do {
let jsonData = try NSJSONSerialization.dataWithJSONObject(json, options: .PrettyPrinted)
// create post request
let url = NSURL(string: link)!
let request = NSMutableURLRequest(URL: url)
request.HTTPMethod = "POST"
// insert json data to the request
request.setValue("application/json; charset=utf-8", forHTTPHeaderField: "Content-Type")
request.HTTPBody = jsonData
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
let task = NSURLSession.sharedSession().dataTaskWithRequest(request){ data, response, error in
if error != nil{
print("Error 55 -> \(error)")
return
}
do {
let result = try NSJSONSerialization.JSONObjectWithData(data!, options: []) as? [String:AnyObject]
print("FIRST PRINT -> \(result!["password"])")
novi = String(result!["password"])
//return result
} catch {
print("Error 43-> \(error)")
}
}
task.resume()
}
catch {
//handle error. Probably return or mark function as throws
print(error)
}
print("SECOND PRINT -> \(novi)")
如果看到
print(“第一次打印->\(结果![“密码”])”)
,它将正常执行并输出所有变量。然后,如果在代码末尾看到print(“SECOND print->\(novi)”)
,它会输出空的sting,就像我没有给它赋值一样 您正在使用异步块。print语句将在块有机会设置novi之前运行
此问题不是do catch的问题,而是异步问题。这是“dataTaskWithRequest异步执行”问题的另一个变体,与do catch无关。我刚刚为您修改了答案。请看一下这个代码。阿尔文-我如何调用函数,完成对我来说是新的东西