[ios] Added show alert to common view controller.

iphone/Maps/ViewController.h

@@ -1,5 +1,6 @@
 @interface ViewController : UIViewController
 
 - (void)refresh;
+- (void)showAlert:(NSString *)alert withButtonTitle:(NSString *)buttonTitle;
 
 @end

iphone/Maps/ViewController.mm

@@ -1,7 +1,8 @@
+#import "Common.h"
 #import "MapsAppDelegate.h"
 #import "MapViewController.h"
 #import "ViewController.h"
-#import "../../3party/Alohalytics/src/alohalytics_objc.h"
+#import "3party/Alohalytics/src/alohalytics_objc.h"
 
 @implementation ViewController
 
@@ -36,4 +37,28 @@
   [super viewWillDisappear:animated];
 }
 
+- (void)showAlert:(NSString *)alert withButtonTitle:(NSString *)buttonTitle
+{
+  if (isIOSVersionLessThan(8))
+  {
+    UIAlertView * alertView = [[UIAlertView alloc] initWithTitle:alert
+                                                         message:nil
+                                                        delegate:nil
+                                               cancelButtonTitle:buttonTitle
+                                               otherButtonTitles:nil];
+    [alertView show];
+  }
+  else
+  {
+    UIAlertController * alertController =
+        [UIAlertController alertControllerWithTitle:alert
+                                            message:nil
+                                     preferredStyle:UIAlertControllerStyleAlert];
+    UIAlertAction * okAction =
+        [UIAlertAction actionWithTitle:buttonTitle style:UIAlertActionStyleCancel handler:nil];
+    [alertController addAction:okAction];
+    [self presentViewController:alertController animated:YES completion:nil];
+  }
+}
+
 @end