Making a View Controller without storyboard, without xibs

Let’s walk through building a ViewController entirely in code.

Large portions of this tutorial were borrowed from iOS7 Programming Cookbook- check it out on Amazon.com if you are interested in trying out pure code examples by yourself

This isn’t as hard nor scary as it would initially seem..

Lets create an Empty application, then add on a ViewController file. You need the file, because that’s what we’ve always needed with storyboard, and xib files. Once you have that import the “ViewController.h” file into your AppDelegate implementation.

Okay- now that we have that, we need to tell the AppDelegate what to do with it.

Did you guess what we needed next? If you guessed a ViewController property then know I am cheering for you!

Scroll down and find application:didFinishLaunchingWithOptions method. It returns a BOOL and should be the first one. Initialize the vc property and set it to be the rootViewController.

Since I asked it to place blue as the backgroundColor of self.window, this is what we get:

So wait- how do we really know that it worked? I’m glad you asked!

Lets hop into the ViewController and throw down something… anything is fine!

The only issue you should be aware of is once you start doing things programmatically, the rest should be programmatic as well!

I dropped in a UISlider property, set its size, placed it in the center, min/max values, and added it to the subview of the ViewController all within the ViewController implementation file. AppDelegate doesn’t know it exists.

Not so bad. Feelin nice!

Thank you.

Is there another way?

Yesterday I had a drunken rant of a post describing how much I detest blocks, this morning I sobered up and started to research another method for multithreading. Surely there has got to be one, right? Good thing is there IS a way to multithread your application without using blocks, each with their own advantages and disadvantages. Glancing at a fantastic book iOS Components and Frameworks gave a really solid review. Lets list them:

1 the Selector:

The selector gives us an opportunity to run code and bounce back between threads.

 

Pros: very easy on the eyes, intuitive

Cons: completion of tasks are unpredictable, chaotic, and out of order

Pretty much whatever data you put into the thread can come back out of order. If merely updating your interface is important without regard to FIFO, this should suffice. Generally, we want an order so we can try again with a different method

NSOperationQueue is a bit more involved, and it requires blocks, but smaller more manageable ones. We can begin by creating a property NSOperationQueue

 

alloc, init like we are supposed to in viewDidLoad

 

then use viewDidAppear for declaring the selector, and instantiate your invocationOperation using the selector you just created as a parameter and pass a nice NSLog message:

 

 

Pros: Keeps thread returns coming back in order

Cons: more code, selectors and BLOCKS (??)

Ironically block syntax is starting to grow on me after I try to find methods that avoid them. And the methods that are supposed to avoid them still use them.

There is one more which I’d like to share, dispatch_async(someVar, ^{/*block syntax*/});

 

These are blocks, I know. It looks like old-school C and upon reflection it is probably what scared me away from actually enjoying them.

Pros: Allows more flexibility and customization

Cons: Not beginner-friendly.

This blogger will try and research block syntax (especially dispatch_async) over the next few days. Wish me luck

**also- do yourself a favor and buy iOS Components and Frameworks. Lots of fun for developers of all ages

(void)(^IveBeenBlocked)(NSArray *confusingTopics, NSDictionary *descriptiveAdjectives);

Yesterday I felt pretty good about blocks, today I feel like descriptiveAdjective[@”cussWord”]. Exactly.

Lets say we have a completion handler which requires NSData, NSURLResponse, and NSError to be passed in as arguments. The syntax would look like:
^(NSData *data, NSURLResponse *response, NSError *error) {…}
but note inside the block only the data parameter is used…
<code=”objc”>
{
// inside the block
NSArray *responseArray = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
NSMutableArray *issues = [NSMutableArray new];
for (NSInteger i = 0; i < [responseArray count]; i++) {
NSDictionary *firstIssueDictionary = responseArray[i];
Issue *newIssue = [[Issue alloc] init];
newIssue.title = firstIssueDictionary[@”title”];
newIssue.uniqueID = firstIssueDictionary[@”id”];
newIssue.htmlURL = [NSURL URLWithString:firstIssueDictionary[@”html_url”]];
[issues addObject:newIssue];
NSLog(@”Aww Yeah\n%@”, newIssue);
}
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
}];
}];
</code>
Okay? I feel

Lets take a look at this: making blocks into typedefs

We had a project (which was a tad more intuitive) where the goal was to remake the delegate methods of UIAlertView into blocks. A bit more understandable, because if you see here:

– (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex

– (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex

– (void)alertView:(UIAlertView *)alertView willDismissWithButtonIndex:(NSInteger)buttonIndex

they all do different things, but they share the same return type and arguments. So we can place them all into a typedef block:

typedef void (^TheBlock)(UIAlertView *alertView, NSInteger index);

Apple wants us to create blocks like this:

Whuuut? Why bother with that when we have functions that can do the same thing?

int multiplier = 7;

– (int) myMethod:(int)num andMultiplier:(int)multiplier

{

        return num * multiplier;

}

Doesn’t that look easier?

Stop it Apple. STOP IT!

Saw a snippet of Lynda.com and that helped a bit. More like a tad.

basic block:

return type       name       param     block literal

      int            (^myBlock) (int) = ^(int a) {….};

According to Lynda, we can drop the return type, name, and parameter at the left of the equals sign and just keep the literal. So this is all:

^(int a) {….};

looks better, feels better.

While watching iTunes U, they used blocks only for Multithreading. Shown here:

and here:

So here the blocks are only handling URL sessions. Which makes sense, if we want to wait for a website to load, the user could believe that our app crashed. So our app gets a low rating. Blocks allow us to do something else while whatever data we need is still loading behind the scenes, on another thread. The only saving grace of blocks is here.

Apple, don’t do it.

**Disclaimer WordPress is awful- I had to type this out a second time losing heaps of content because for some ridiculous reason at 9:40pm this website did not properly save my first draft and posted half of the blog. Yeah you heard me WordPress. Fix It!

Multithreading

This is something I have been dodging because of block syntax. Don’t see it very often, nor do I understand its purpose- until now.

Most apps nowadays use wireless internet. Sometimes in our haste to deploy a functioning app we forget that our devices will only process one thing at a time, unless we direct it to do otherwise. For my example, I will be borrowing heavily from the iTunes U Stanford lecture #10.

While the main focus of this lesson is the scroll view, another important lesson to gain here is that we make a call for some remote data, there will be a pause. Users hate pauses, and it causes unpredictable, rash behavior.

Let’s say we made an app that downloads a file off the internet. This isn’t a regular file, but a very large photo.

images.apple.com/v/iphone-5s/gallery/a/images/download/photo_1.jpg

images.apple.com/v/iphone-5s/gallery/a/images/download/photo_2.jpg

images.apple.com/v/iphone-5s/gallery/a/images/download/photo_3.jpg

images.apple.com/v/iphone-5s/gallery/a/images/download/photo_4.jpg

Okay- we set it up in the View Controller and everything looks great. Outlets plugged, etc.

okay. Lets press the button and watch the magic happen!

What’s going on? As mentioned earlier, the app is waiting for our picture to download before giving the ‘OK’ to move to the next scene.

Enter Blocks!

 Not these blocks

This is a block. (props to GoshDarnBlockSyntax.com)

Taking my code from this:

To this:

looks more complicated, and it is (believe me!) But with good reason.

While everything happens (user presses the button) the block will step up and download the image you want in the background. It will let the user retain control of the app by making choices and staying out of a “Frozen” state. Remember, for our users a frozen app is synonymous with crashing, so try to avoid as much as possible!

We also have NSOperationQueue which is separate from the C function dispatch_async() used in the snippet above. Depending on your preference or comfort with C you may wish to use [NSOperationQueue mainQueue] instead of dispatch_async().

JSON vs XML

Good day!

Today I would like to discuss some data formats which several developers interact with constantly. Since we have many types of data to store, with varying ways to update and build upon, organization can quickly get messy. Thankfully someone came up with a method to fix the madness when we need to call a database and fetch results. Let’s get started.

XML or ‘Extensible Markup Language’ was introduced February 10, 1998. NSXMLParser is the ‘Apple approved’ way to go for parsing the document which looks like this:

XML is described as a ‘meta language’ which allows the user to create their own vocabulary pertaining to the information.

I see it as being very similar to object-oriented type design, in the way we have a collection of ‘Books’ in the picture above, the developer can add a ‘Book ISBN’ with title & author, similar to how objects with their respective properties are formed from classes.

Best thing about it is the popularity. XML is so widely used you can’t avoid learning about it!

Bad thing about XML is the formatting. Everything is ‘tagged’, so we need an open format<blah>, closing </blah> tag which must match or BOOM text spaghetti.

JSON stands for JavaScript Object Notation which this author must confess he enjoys looking at over XML. JSON is quite versatile as a data-storing document, with the ability to hold objects, arrays, values, and strings. Not as explicit as XML, JSON is more subtle.

sorry if this is difficult to see!

so at the top of our chain, we have ‘response’ which holds a dictionary  ‘groups’ that holds an array of dictionaries ‘type’, ‘name’, ‘items’ and so on and so forth.

JSON can quickly become very complex without bloating visibility. NSJSONSerialization is the class used to parse your JSON file making dictionary handling a touch easier.

Best thing about JSON is that it is quickly gaining traction. Foursquare, Yahoo, Google, MongoDB and several others are incorporating its use for data handling, and it is easy to learn from www.json.org

 

A change in plan…

I was going to start off with a discussion about JSON, but when I started working on a project it got me really excited. This week lets chat about UIKit Dynamics!

What is it?

UIKit Dynamics

Apple has figured out a way to manage a physics engine in iOS Foundation Like A Boss

lets discuss a little of what it does exactly:

It manages gravity (things must fall), collisions (things are gonna crash, sometimes), attachments, springs, snap, force (think like a Jedi) plus they inherit properties allowsRotation, density (affects gravity and collision reactions), elasticity (bounce), and resistance.

For some of these things, you may have had a taste of it already on your lock screen.

swipe Down

So if you swipe lightly, it won’t fall. Swipe harder and it falls with a gentle bounce at the bottom.

That’s UIDynamicAnimator, UIGravityBehavior, and UICollisionBehavior all for you folks!

Same occurs at the bottom with the camera, the lock slide, and the control center.

to see the code which you need to call, first and foremost the UIDynamicAnimator

one way calling the delegate and property

@interface ViewController () <UIDynamicAnimatorDelegate>

@property (strong, nonatomic) UIDynamicAnimator *animator;

another way is to call the class, alloc and init

UIDynamicAnimator *animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];

[animator addBehavior:someDynamicBehavior];

UIGravityBehavior works just the way you would imagine:

It will make things fall. They will fall toward the home button, no matter which way the phone orientation is.

to fix this there is a method called setGravityDirection:CGVectorMake(x float, y float) which can “sway” the direction of -whatever- is falling in the direction you want. For a drop down action, x stays at 0.0f and y can be any float between 0.1 and 1 (1 making us fall the fastest).

If x is incremented to 0.1, our object will “fall” to the right, -0.1 and it “falls” to the left.

If y is made negative, it will “fall” up.

It makes me curious if we could tap into the gyroscope and make our “falling” dynamic?

Second, it should be noted that if we don’t have UICollisionBehavior activated, our object will fall right off the phone! (and out of sight) Lets call that.

UICollisionBehavior *collide = [[UICollisionBehavior alloc] init];

collide.translatesReferenceBoundsIntoBoundary = YES;

Why ‘YES’? Because it’s a BOOL.

Seriously, it will make our view boundary the limit for which things to contact when ‘falling’. Without it we will have no limit, and objects will ‘fall’ right off the phone.

It has been said that UIKit Dynamics and AutoLayout don’t play nicely. Keep them apart until Apple teaches them to share screen real estate (iOS 8?)

Why is this important?

Previous to iOS7, it was not native. We would need an engine imported from somewhere else. For developers, it is easier to make games, or apps that react to your users’ particular movements or touch patters.

props to ComedyCentral, Photobucket, CultOfMac & 3dpop for the pics, iOS Components and Frameworks for some snippets!

Dictionaries in Objective-C

I was asked to write a blog which documents my journey to discovering Objective-C

… and that’s pretty much how I feel right now.

Heard of a dictionary?

dictionary

Something like that. I’m talking about an NSDictionary, which stores objects by key-value pairs.

If that isn’t English enough for you, we have a unique key that points to a value, and save that.

First, lets start with creating one. The standard way to alloc / init

NSDictionary *myDict1 = [[NSDictionary alloc] init];

Second, create one with a literal (if you know what values you want inside)

NSDictionary *myDict2 = @{@"british": @"british English", @"american":@"american English"};

Third, my favorite-

NSDictionary *myDict3 = [NSDictionary dictionary];

please note that the first & third dictionaries will be empty!

Next lets see how we can pull things out of our dictionary.

NSString *murica = [myDict2 objectForKey:@"american"];

so our string name ‘murica’ now is equal to @”american English”

For our friends in the United Kingdom,

NSString *uk = myDict2[@"british"];

so the string name ‘uk’ is now equal to @”british English”.

Remember when I mentioned earlier that dictionaries hold objects? They really do!

can you feel the excitement

That means dictionaries can hold other dictionaries. Is your mind blown? Mine is..

lets look at this in detail:

NSDictionary *muppets = @{@"Muppets":@{@"Kermit":@"the frog"}, @{@"Statler":@"the sleepy old dude that complains and hates"}, @{@"Waldorf":@"the mean looking old dude that complains and hates"}, @{@"Fozzie":@"a bear that makes awful jokes"}}

so for our dictionary Muppets, we are holding the keys ‘Kermit’, ‘Statler’, ‘Waldorf’, and ‘Fozzie’, with their respective values.

For accessing the objects within the dictionary, here is a short project
https://github.com/FullMetalFist/PlayingWithDictionaries

there is more than one way to access the values in the dictionary “theDict”

someMuricanWord = [[theDict objectForKey:@"american"] objectForKey:@"airplane"];
someBritWord = theDict[@"british"][@"behaviour"];

easy like a sunday morning, right?

Sources:

https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/Reference/Reference.html

http://rypress.com/tutorials/objective-c/data-types/nsdictionary.html

http://cocoaheads.tumblr.com/post/17757846453/objective-c-literals-for-nsdictionary-nsarray