#iphonesdk

[tweakingios-blog]

How to get the size of Keyboard when any UITextView or UITextField is enabled? (Come iOS8 and third-party keyboards, this is going to be very important)

Till iOS7, we had just one type of keyboard in iPhone/iPad. But finally with iOS8, we will be having third party keyboards which can be used throughout the device. Can't wait to install this on my iPhone.

However, many developers have been using a static size to get the size of keyboard heights, which is not a good idea! Come iOS8, this just worsens the situation. Solution?

Its right there in your code. Just that you haven't been using it yet. 

You must be having a similar method for subscribing to keyboard notifications.

- (void)registerForKeyboardNotifications {

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasShown:) name:UIKeyboardDidShowNotification object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillBeHidden:) name:UIKeyboardWillHideNotification object:nil];

}

So in your listeners for these notifications, get this value :

- (void)keyboardWasShown:(NSNotification*)aNotification {

NSDictionary* info = [aNotification userInfo]; CGSize keyboardSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size; //this gives the exact size of the keyboard currently used

}

Hope this helps!

Keep coding! 

[tweakingios-blog]

So what's the difference between a message, a selector and a method in Objective C?

Selector - a Selector is the name of a method. You're very familiar with these selectors: alloc, init,release, dictionaryWithObjectsAndKeys:, setObject:forKey:, etc. Note that the colon is part of the selector; it's how we identify that this method requires parameters. Also (though it's extremely rare), you can have selectors like this: doFoo:::. This is a method that takes three parameters, and you'd invoke it like [someObject doFoo:arg1 :arg2 :arg3]. There's no requirement that there be letters before each part of the selector components. As I said, this is extremely rare, and you will not find it used in the Cocoa frameworks. You can work with selectors directly in Cocoa. They have the type SEL: SEL aSelector = @selector(doSomething:) or SEL aSelector = NSSelectorFromString(@"doSomething:");

Message - a message is a selector and the arguments you are sending with it. If I say [dictionary setObject:obj forKey:key], then the "message" is the selector setObject:forKey: plus the arguments obj and key. Messages can be encapsulated in an NSInvocation object for later invocation. Messages are sent to a receiver. (ie, the object that "receives" the message).

Method - a method is a combination of a selector and an implementation (and accompanying metadata). The "implementation" is the actual block of code; it's a function pointer (an IMP). An actual method can be retrieved internally using a Method struct (retrievable from the runtime).

Some other related things:

Method Signature - a method signature represents the data types returned by and accepted by a method. They can be represented at runtime via an NSMethodSignature and (in some cases) a raw char*.

Implementation - the actual executable code of a method. Its type at runtime is an IMP, and it's really just a function pointer. iOS 4.3 includes a new ability to turn a block into an IMP. This is really cool.

One of the fun things to realize is that the name of a method (the selector) is distinct from the implementationof the method (the IMP). This means that you can swap them around, if you're feeling daring. You can also add and remove methods at runtime, because all you're doing is editing an entry in a hash table: the key is the selector, and the value is the IMP of the method. This allows you to do some really crazy and trippy stuff.

Via - Dave DeLong's answer to this question on StackOverflow!

[tweakingios-blog]

Top 5 iOS Developer Podcasts

MUST SUBSCRIBE!

[tweakingios-blog]

Ever faced the error "ImageIO: JPEG Application transferred too few scanlines" ? Don't worry. You have a solution!

This error comes up due to two reasons.

1. Maybe you are downloading a .JPEG image and saving it as a .PNG image

Otherwise,

(Most probable one) 2. You are accessing your stored image with the function imageWithContentsOfFile like this : 

UIImage *myImage = [UIImage imageWithContentsOfFile:path];

Instead, fetch data from that file and then create image from that nsdata :

NSData *img = [NSData dataWithContentsOfFile:path]; UIImage *photo = [UIImage imageWithData:img];

Looks like the function imageWithContentsOfFile keeps the file open till the UIImage stays allocated. Hence this much memory stays allocated without any use of it.

  Happpy Coding! :)

[shabzcode-blog]

Follow a username on Twitter iOS 5+

This easy snippet allows you to specify a username you'd like your users to follow. For instance, in an About page you can add a "Follow Me" button that checks the users logged in twitter accounts and follows you with the first available account.

Simply use:

[self follow:@"shabzcohelp"];

-(void) follow:(NSString *) username { if ([TWTweetComposeViewController canSendTweet]) { // Create account store, followed by a twitter account identifier ACAccountStore *accountStore = [[ACAccountStore alloc] init]; ACAccountType *type = [accountStore accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter]; [accountStore requestAccessToAccountsWithType:type withCompletionHandler:^(BOOL granted, NSError *error) { if(granted) { NSArray *accountsArray = [accountStore accountsWithAccountType:type]; // Sanity check if ([accountsArray count] > 0) { //Create dictionary to pass to followWithAccountInfo: method NSMutableDictionary *dict = [NSMutableDictionary dictionary]; [dict setObject:username forKey:@"usernameToFollow"]; //Follow the username with your first logged in account [dict setObject:[accountsArray objectAtIndex:0] forKey:@"account"]; [self performSelectorOnMainThread:@selector(followWithAccountInfo:) withObject:dict waitUntilDone:NO]; } else { //No Accounts Available } } }]; } } -(void) followWithAccountInfo:(NSDictionary *) dictionary { ACAccount *acct = [dictionary objectForKey:@"account"]; NSString *username = [dictionary objectForKey:@"usernameToFollow"]; // Build a twitter request for following the username specified TWRequest *postRequest = [[TWRequest alloc] initWithURL: [NSURL URLWithString:@"http://api.twitter.com/1.1/friendships/create.json"] parameters:[NSDictionary dictionaryWithObjectsAndKeys:username, @"screen_name", @"true", @"follow", nil] requestMethod:TWRequestMethodPOST]; // Post the request [postRequest setAccount:acct]; // Block handler to manage the response [postRequest performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) {NSLog(@"%d", urlResponse.statusCode); [postRequest release];}]; }

[shabzcode-blog]

iOS 6 SupportedOrientations with UINavigationController

You probably already know that -shouldAutorotateToInterfaceOrientation had been deprecated in iOS 6 and we were told to move to -shouldAutorotate and -supportedInterfaceOrientations, but me and apparently many others on SO and on the Apple forums were having trouble if the rootViewController in the AppDelegate was anything besides a UIViewController.

So here's my solution that could probably work if you subclassed UITabBarController also.

My subclassed UINavigationController that is Orientation Aware of it's top-most ViewController.

(I will provide the class files at the bottom of the post)

So First of all you'll override these 2 methods so that the top viewcontroller of the hierarchy will take control of the orientation.

-(NSUInteger)supportedInterfaceOrientations { return [self.topViewController supportedInterfaceOrientations]; } -(BOOL)shouldAutorotate { return YES; }

Now whichever ViewController's you don't want to rotate add these lines of code.

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { return (interfaceOrientation == UIInterfaceOrientationPortrait); } -(BOOL)shouldAutorotate { return NO; } -(NSUInteger)supportedInterfaceOrientations { return UIInterfaceOrientationMaskPortrait; }

And for any ViewController that you do want to be able to rotate and code like this

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown); } -(NSUInteger)supportedInterfaceOrientations { return UIInterfaceOrientationMaskAllButUpsideDown; } -(BOOL)shouldAutorotate { return YES; }

Here are the class files for the Orientation-aware UINavigationcontroller

[shabzcode-blog]

Easy way to check if current device is iPhone 5 or new iPod Touch

if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) { CGSize result = [[UIScreen mainScreen] bounds].size; if(result.height == 480) { // iPhone Classic } if(result.height == 568) { // iPhone 5 or new iPod Touch } }

[kazu69]