iOS HttpClient crash

HttpClient client = new HttpClient();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            var jsonstring = await client.GetStringAsync("https://asdasdadasd" + url);

Causes this error:

2019-03-29 11:18:43.901 Eliant.App.iOS[3859:3548233] [AppCenterCrashes] ERROR: +[MSWrapperLogger MSWrapperLog:tag:level:]/7 Unhandled Exception:
UIKit.UIKitThreadAccessException: UIKit Consistency error: you are calling a UIKit method that can only be invoked from the UI thread.
at UIKit.UIApplication.EnsureUIThread () [0x00020] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.6.0.16/src/Xamarin.iOS/UIKit/UIApplication.cs:89
at UIKit.UIGestureRecognizer.RemoveTarget (Foundation.NSObject target, System.IntPtr action) [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.6.0.16/src/Xamarin.iOS/UIKit/UIGestureRecognizer.g.cs:342
at UIKit.UIGestureRecognizer.OnDispose () [0x00016] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.6.0.16/src/Xamarin.iOS/UIKit/UIGestureRecognizer.cs:41
at UIKit.UIGestureRecognizer.Dispose (System.Boolean disposing) [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.6.0.16/src/Xamarin.iOS/UIKit/UIGestureRecognizer.g.cs:959
at
Foundation.NSObject.Finalize () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.6.0.16/src/Xamarin.iOS/Foundation/NSObject2.cs:143

Any ideas?

Commenting out await client.GetStringAsync() makes the app work fine. I've tried running it using Device invoke on main thread (even though i dont think there is any reason i should need to do that?) i've tried .result instead of await, and i've tried getasync().content.readstringasync and always have the same issue.