Archive for the ‘CodeSnippets’ Category

UINavigationBar Color of More Tab in iOS 5

If you start a Tabbed Application and use Storyboards in Xcode with iOS 5 a simple project will be created with two tabs. If you add more than 5 Tabs to the Tab Bar Controller a “More” tab will be created automatically.

The NavigationBar in the More Tab and the modal view (edit) are colored with default blue. To change the color of the moreNavigationController you have to do the following steps.

Extend app delegate so that it implements the UIApplicationDelegate and UITabBarControllerDelegate protocols.

#import <UIKit/UIKit.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate, UITabBarControllerDelegate> {

 UIWindow *window;
 UITabBarController *tabBarController;

@property (nonatomic, retain) UIWindow *window;
@property (nonatomic, retain) UITabBarController *tabBarController;


The app delegate doesn’t know anything about the ViewControllers yet, so it will have to dig through the storyboard to find it. With Interface Builder you always had a reference to the App Delegate in your MainWindow.xib and you could make connections from your top-level view controllers to outlets on the App Delegate. That is currently not possible with storyboards. You cannot make references to the app delegate from your top-level view controllers. So you have to get those references programmatically. You know that the storyboard’s initial view controller is a Tab Bar Controller, so you can look up the window’s rootViewController and cast it.

UITabBarController *tabBarController = (UITabBarController *)

Then you can get the More Tab by the Tab Bar Controller and  set a color.

UINavigationController *moreController = tabBarController.moreNavigationController;
moreController.navigationBar.tintColor = [UIColor orangeColor];

After that you use the App Delegate as the delegate of the Tab Bar and change the color of the “Edit” View, too.

tabBarController.delegate = self;
UIView *editView = [controller.view.subviews objectAtIndex:1];
 UINavigationBar *modalNavBar = [editView.subviews objectAtIndex:0];
 modalNavBar.tintColor = [UIColor orangeColor];

The complete code of AppDelegate.m:

#import "AppDelegate.h"

@implementation AppDelegate

@synthesize window = _window;
@synthesize tabBarController;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 // Get top-level view controller reference programmatically
 tabBarController = (UITabBarController *) self.window.rootViewController;

 // Set the color of the navigationbar in moretab
 UINavigationController *moreController = tabBarController.moreNavigationController;
 // //moreController.navigationBar.barStyle = UIBarStyleBlackOpaque;
 moreController.navigationBar.tintColor = [UIColor orangeColor];
 moreController.navigationBar.hidden = NO;
 moreController.navigationBar.backgroundColor = [UIColor blackColor];

 // Set delegate of the tabBarController to handle the UITabBarControllerDelegate calls
 tabBarController.delegate = self;

 return YES;

- (void) tabBarController:(UITabBarController *)controller willBeginCustomizingViewControllers:(NSArray *)viewControllers {

 // Set the color of the navigationbar if edit was selected
 UIView *editView = [controller.view.subviews objectAtIndex:1];
 UINavigationBar *modalNavBar = [editView.subviews objectAtIndex:0];
 modalNavBar.tintColor = [UIColor orangeColor];


Here you can download the example Project.

Categories: CodeSnippets, Development, iOS

Case insensitive comparison and searching NSString

if( [@"Some String" caseInsensitiveCompare:@"some string"] == NSOrderedSame ) {
   // strings are equal except for possibly case

NSRange range = [@"Some String" rangeOfString:@"string" options:NSCaseInsensitiveSearch];
if (range.location != NSNotFound) {
   // String found
Categories: CodeSnippets, Development, iOS

Converting NSString to NSDate and vice versa

NSDate *date = [NSdate date];

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd"];

// Convert a date to NSString and get rid of the minutes...
NSString *strDate = [dateFormatter stringFromDate:date];

// Convert it back to NSDate
NSDate *newDate = [dateFormatter dateFromString:strDate];
Categories: CodeSnippets, Development, iOS

Check if view is visible

if (self.navigationController.visibleViewController == self) {}
Categories: CodeSnippets, Development, iOS

NSString Basics

Creating strings

NSString *myFirstString = @"foo";
NSString *mySecondString = [[NSString alloc] initWithFormat:
   @"%@%@%@i", myFirstString, @"bar", 1];

Comparing strings

NSString *myString = @"foo";
if([myString isEqualToString:@"foo"]) {
   NSLog (@"Strings are equal!");

Finding strings within strings

NSString *myString = @"foo";
NSString *searchForMe = @"Howdi";
NSRange range = [myString rangeOfString : searchForMe];
int location = range.location;
int length = range.length;

if (location != NSNotFound) {

   NSString *locationAndLength = [[NSString alloc] initWithFormat:
      @"Location: %i, length: %i", location, length];
   NSLog(@"I found something.");

Replacing strings within strings

NSString *myString = @"foo";
myString = [myString stringByReplacingOccurancesOfString:@"oo"

Extracting substrings from strings

There are 3 methods that allow to extract substrings from a parent string:

  • -substringToIndex:
  • -substringWithRange:
  • -substringFromIndex: (which respectively take a substring from the beginning, middle, and end of a parent string)

The first method substringToIndex returns a new string which is composed of the characters from the beginning of the receiver string up to (but not including) the character at the specified index:

NSString *aString = @"Running out of ideas for strings.";
NSString *substring = [aString substringToIndex:7];
// result: @"Running"

The method substringFromIndex works in the same way, except now the substring starts at the specified index of the receiver (including the character at the index) and includes all the characters to the end of the receiver:

NSString *substring = [aString substringFromIndex:25];
// result: @"strings"

Finally, we have the method which lets us arbitrarily extract a substring from anywhere within the parent string substringWithRange. The argument to this method is an NSRange:

NSString *substring = [aString substringWithRange:NSMakeRange(15, 5)];
// result: @"ideas"

Here the range starts with the 15th character, “i”, and extends to include the next four characters, giving us a length of 5, “ideas”.

How to find class type of an object

February 1, 2011 1 comment
NSLog(@"Is of type: %@", [myObject class]);
NSLog(@"Is of type NSString?: %@", ([[myObject class] isMemberOfClass:
                                    [NSString class]])? @"Yes" : @"No");
NSLog(@"Is a kind of NSString: %@", ([[myObject classForCoder]
                  isSubclassOfClass:[NSString class]])? @"Yes" : @"No");

Location via GPS with iOS

First add the Core Location framework:

  • right click on the “Frameworks” group and go to Add > Existing Frameworks…
  • select the CoreLocation.framework

Then you can use the framework in your app:

#import <CoreLocation/CoreLocation.h>

@interface MyLocation : NSObject <CLLocationManagerDelegate> {
	CLLocationManager *locationManager;

#import "MyLocation.h"

@implementation MyLocation

- (id) init {
   if ((self = [super init])) {
      // Custom initialization
      locationManager = [[CLLocationManager alloc] init];
      locationManager.delegate = self;
      locationManager.distanceFilter = kCLDistanceFilterNone;
      locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters;
     [locationManager startUpdatingLocation];
   return self;

- (void) locationManager:(CLLocationManager *)manager
   didUpdateToLocation:(CLLocation *)newLocation
   fromLocation:(CLLocation *)oldLocation {

   int degrees = newLocation.coordinate.latitude;
   double decimal = fabs(newLocation.coordinate.latitude - degrees);
   int minutes = decimal * 60;
   double seconds = decimal * 3600 - minutes * 60;
   NSString *lat = [NSString stringWithFormat:@"%d° %d' %1.4f\"", 
                         degrees, minutes, seconds];

   degrees = newLocation.coordinate.longitude;
   decimal = fabs(newLocation.coordinate.longitude - degrees);
   minutes = decimal * 60;
   seconds = decimal * 3600 - minutes * 60;
   NSString *lon = [NSString stringWithFormat:@"%d° %d' %1.4f\"", 
                         degrees, minutes, seconds];
Categories: CodeSnippets, iOS, Objective-C