[Journey In App Creation]Post 4- Showing The Errors

So now that we got the data, we left some TODOs to handle at a later time. Lets start completing them. They aren't hard, I just wanted to finish up the data retrieval and parsing out before going onto other topics.

Lets start with the label that'll show errors. Lets add that onto our view and then connect it.

if name == ""
        {
            //TODO: Notify User That They Didn't Enter A Username
            errorLabel.text = "Please Input A Name"
            print("No Name Entred")
            return
        }

Running the app and pressing submit without putting in a name now works. But we run into another problem. When we first launch the app up, the label is there just saying "Error Label". So we need to hide it. When that screen is launched, the code within viewDidLoad happen. So we can set the label to be hidden when its launched. So lets do that. All we need to do is add : errorLabel.isHidden = true inside viewDidLoad.

But doing that will cause a problem. It'll remain hidden even when we change the text inside it to show the user the error. To do that, we unhide it. Thats as simple as errorLabel.isHidden = false. So all we would need to do is put that a line before changing the text of it.

Now if the user keeps pressing the button with no text inside the textField, the message won't change. To show the user that, we'll flash the screen red for 0.01 seconds. To do that, we'll first set the view's background color to red, the on a thread we have something thats done after 0.01 seconds. Thats written as:

self.view.backgroundColor = .red
DispatchQueue.main.asyncAfter(deadline: .now() + 0.01) {
     self.view.backgroundColor = .white
     }

We get a result like this:

_{Due to the speed of the flash, its near impossible to see it with a gif. You can sort of make it out.}

Now we are just doing something similar everywhere else, just with a different message. So we can make this into a function so we don't have to keep repeating ourselves. Lets do that.

func showError(message: String)
    {
        self.errorLabel.isHidden = false
        errorLabel.text = message
        self.view.backgroundColor = .red
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.01) {
            self.view.backgroundColor = .white
        }
    }

Functions in swift are declared with func. The message: String part is the parameter. It shows that the message paramour that you pass has to be of type String.

We can call that function with : showError(message: "Please Input A Name"). Lets do that for all the other errors, but replacing the message with what we need the message to be.

After we do that, we just have to rehide the label if we do get data back and no errors happen. So lets put the code to hide the label right before we start parsing the data out.

Lets run some tests. Yup, it all works out perfectly. Thats all for the day guys. Just some simple stuff. On the next post I'll start displaying the data. Here's all of what we have so far:

import UIKit
import Alamofire

class NameVC: UIViewController
{

    @IBOutlet weak var nameTextField : UITextField!
    @IBOutlet weak var errorLabel: UILabel!
    
    override func viewDidLoad()
    {
       errorLabel.isHidden = true
    }
    
    @IBAction func submitButtonAction(_ sender: UIButton)
    {
        let name = nameTextField.text
        
        if name == ""
        {
            showError(message: "Please Input A Name")
            return
        }
        
        Alamofire.request("http://localhost:8080/?" + name!, parameters: nil, headers: nil).responseJSON { response in
            if response.value == nil
            {
                self.showError(message: "We didn't get any data back.")
                return
            }
            
            let responseDict : [String: Any] = response.value as! [String : Any]
            print(responseDict)
            let message = responseDict["message"] as! String
            
            if message == "fail"
            {
                self.showError(message: "User doens't exist")
                return
            }
            
            self.errorLabel.isHidden = true
            let vp = (responseDict["vp"] as! NSString).floatValue
            let liquidSteem = (responseDict["liquidSteem"] as! NSString).floatValue
            let savingSteem = (responseDict["savingSteem"] as! NSString).floatValue
            let liquidSBD = (responseDict["liquidSBD"] as! NSString).floatValue
            let savingSBD = (responseDict["savingSBD"] as! NSString).floatValue
            
            print(vp, liquidSteem, savingSteem, liquidSBD, savingSBD)
                
        }
        
    }
    
    func showError(message: String)
    {
        self.errorLabel.isHidden = false
        errorLabel.text = message
        errorLabel.textAlignment = .center
        self.view.backgroundColor = .red
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.01) {
            self.view.backgroundColor = .white
        }
    }
    

}

Edit: I forgot to put in the contest for SBI. So um, here's one. Other than Carthage, whats the other popular dependency manager for iOS apps(hint it begins with the same letter)?