iOS: Add very basic diagnostic screen

Summary:
Adds an extremely barebones in-app screen for showing sonar diagnostics.
The UI is laughable, but it's wired up. Leaving proper design to a later commit.

Like in the android case, state is currently passed as a string, but will become something much more structured after this is in place.

Reviewed By: priteshrnandgaonkar

Differential Revision: D9218766

fbshipit-source-id: 4889ed79b928056a67b1e8cb8a40a9bd52e084f1

iOS/SonarKit/FlipperDiagnosticsViewController.m

@@ -0,0 +1,39 @@
+#ifdef FB_SONARKIT_ENABLED
+
+#import "FlipperDiagnosticsViewController.h"
+#import "SonarClient.h"
+
+@implementation FlipperDiagnosticsViewController
+
+- (void)viewDidLoad {
+  [super viewDidLoad];
+
+  UILabel *text = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 50)];
+  text.text = @"Flipper Diagnostics";
+  [self.view addSubview:text];
+
+  self.scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 50, self.view.frame.size.width, self.view.frame.size.height - 50)];
+  self.stateLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 1000)];
+  self.stateLabel.numberOfLines = 0;
+  self.stateLabel.text = [[SonarClient sharedClient] getState];
+  [self.scrollView addSubview:self.stateLabel];
+  self.scrollView.contentSize = self.stateLabel.frame.size;
+  [self.view addSubview:self.scrollView];
+}
+
+- (void)onUpdate {
+  self.stateLabel.text = [[SonarClient sharedClient] getState];
+  self.scrollView.contentSize = self.stateLabel.frame.size;
+}
+
+- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
+  return UIInterfaceOrientationMaskPortrait;
+}
+
+- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
+  return UIInterfaceOrientationMaskPortrait;
+}
+
+@end
+
+#endif