void ConfigrationUI() { ContactTextField = new UITextField { BackgroundColor = UIColor.Clear, Placeholder = "Please input a contact", TextColor = UIColor.Black, Font = UIFont.SystemFontOfSize(15), LeftView = new UILabel { Frame = new CoreGraphics.CGRect(0, 0, 80, 40), BackgroundColor = UIColor.Clear, Text = "Contact", TextColor = UIColor.Black, Font = UIFont.BoldSystemFontOfSize(14) }, LeftViewMode = UITextFieldViewMode.Always }; View.AddSubview(ContactTextField); SendMessageTextField = new UITextField { BackgroundColor = UIColor.Clear, Placeholder = "Please input a message", TextColor = UIColor.Black, Font = UIFont.SystemFontOfSize(15), LeftView = new UILabel { Frame = new CoreGraphics.CGRect(0, 0, 80, 40), BackgroundColor = UIColor.Clear, Text = "Msg", TextColor = UIColor.Black, Font = UIFont.BoldSystemFontOfSize(14) }, LeftViewMode = UITextFieldViewMode.Always }; View.AddSubview(SendMessageTextField); var sendButton = new UIButton { BackgroundColor = UIColor.Blue, }; sendButton.SetTitleColor(UIColor.White, UIControlState.Normal); sendButton.SetTitle("Send", UIControlState.Normal); sendButton.AddTarget(HandleSendMessageEventHandler, UIControlEvent.TouchUpInside); View.AddSubview(sendButton); TextView = new UITextView { BackgroundColor = UIColor.Clear, TextColor = UIColor.Black, Font = UIFont.SystemFontOfSize(15) }; View.AddSubview(TextView); ContactTextField.MakeConstraints(make => { make.Top.EqualTo(View).Offset(100); make.Left.EqualTo(View).Offset(30); make.Right.EqualTo(View).Offset(-30); make.Height.EqualTo(new NSNumber(45)); }); SendMessageTextField.MakeConstraints(make => { make.Top.EqualTo(ContactTextField.Bottom()).Offset(10); make.Left.EqualTo(View).Offset(30); make.Height.EqualTo(new NSNumber(45)); }); sendButton.MakeConstraints(make => { make.Top.EqualTo(ContactTextField.Bottom()).Offset(10); make.Left.EqualTo(SendMessageTextField.Right()).Offset(15); make.Right.EqualTo(View).Offset(-30); make.Width.EqualTo(new NSNumber(100)); make.Height.EqualTo(new NSNumber(45)); }); TextView.MakeConstraints(make => { make.Top.EqualTo(SendMessageTextField.Bottom()).Offset(20); make.Bottom.EqualTo(View.Bottom()).Offset(30); make.Left.EqualTo(View).Offset(30); make.Right.EqualTo(View).Offset(-30); }); }