Make ninja work with XCTests for iOS.

test/ios/xctests/App/main.m

Index: test/ios/xctests/App/main.m
diff --git a/test/ios/xctests/App/main.m b/test/ios/xctests/App/main.m
new file mode 100644
index 0000000000000000000000000000000000000000..60f7206d25695d8ece27d8b1d3d356fe219a0cc7
--- /dev/null
+++ b/test/ios/xctests/App/main.m
@@ -0,0 +1,9 @@
+#import <UIKit/UIKit.h>
+#import "AppDelegate.h"
+
+int main(int argc, char* argv[]) {
+  @autoreleasepool {
+    return UIApplicationMain(
+        argc, argv, nil, NSStringFromClass([AppDelegate class]));
+  }
+}