Error when clicking any UI element in Xamarin.iOS

Issue

I have an issue with an iOS app I'm working on (https://github.com/nodoid/WeatherApp). It builds and deploys fine but when you hit any UI element that isn't a label, it crashes with an error such as

ViewController btnGetWeather unrecognised selector sent to instance
Error: Objective-C exception thrown. Name: NSInvalidArgumentException Reason: ViewController btnGetWeather unrecognised selector sent to instance

It's been a long time since I've done anything with iOS native (I was still using xibs!). It looks like everything is correct on the storyboard but I'm at a loss as to why this is happening given everything builds.

I've done the usual trick of deleting the obj folder in the iOS project, but still get this issue.

Solution

I downloaded your code to try it out. When I click the button, the error message :Name: NSInvalidArgumentException Reason: Application tried to present modal view controller on itself. Presenting controller is <UIAlertController: 0x7fb648008a00>.

I found the reason for this problem: In the ShowError method of your ViewController.cs, you use the alert.PresentViewController() method, you need to change the alert of this line of code to "this.PresentViewController()".

Answered By - Wen xu Li - MSFT