drruhc4944 2016-08-31 03:34
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如何使用php将iOS应用程序连接到mySQL数据库

So this is the piece of code causing a problem. It gives me a fatal error and says that an optional value is giving nil.

How do i fix this? This only works when I enter the first field only (the name field) and then submit, it pops up on my database. However, when I fill in more than one field, it crashes.

My code:

@IBAction func registerButtonTapped(sender: AnyObject) {

    let strURL: String = "http://www.blabla.com.eg/blabla.php?name=\(nameField.text!)&company=\(companyField.text!)&email=\(emailField.text!)&phonenumber=\(phoneNumberField.text!)"
    let dataURL: NSData = NSData(contentsOfURL: NSURL(string: strURL)!)!
    let strResult: String = String(data: dataURL, encoding: NSUTF8StringEncoding)!
    print("\(strResult)")


    self.dismissViewControllerAnimated(true, completion: nil)

}
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  • dongnan1989 2016-08-31 04:35
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    Your problem is that one (or more) of your optionals is nil when you try to access it. Its important to understand optionals if you are doing swift development, I'd recommend going through the documentation.

    let dataURL: NSData = NSData(contentsOfURL: NSURL(string: strURL)!)!
    let strResult: String = String(data: dataURL, encoding: NSUTF8StringEncoding)!
    

    In the code above, when you use ! you are telling swift that you are 100% sure that optional contains a value. There might be an issue in either your construction of a url NSURL(strUrl)! or when calling the NSData(...) constructor and unwrapping its result with !.

    Try something like this:

    if let url = NSURL(string: strURL) {
       if let data = NSData(contentsOfURL: url) {
           var strResult = String(data: data, encoding: NSUTF8StringEncoding)
           print(strResult ?? "Something Went Wrong")
       }
       else { // get rid of this else when you find your issue
           print("Could not instantiate an NSData object out of that url")
       }
    }
    else {  // get rid of this else when you find your issue
       print("Your URL is nil!, check the strUrl")
    }
    

    Here, we first unwrap the NSURL as NSURL(string) constructor returns an optional (the string you pass might be an invalid URL). We then unwrap the NSData object and then coalesce the strResult when printing it (as its also an optional).

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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