#initializers

Recently i come across with a codebase that were completed blotted with api keys and other settings in code, this was weird because already exists a settings file and it's fairly easy to use it in code. But anyway, was time to fix this.

While changing this mess i encountered what was probably the cause of this. We are using settings logic and the default usage is to create a settings file on models, since usually the files on models aren't configured on autoload they couldn't be used on initialisers.

For this reason, i started to search a solution for this and i come across with this awesome solution.

I think that might be useful for more people, so here it is and it's really easy.

Book: Vol. 1 iOS Programming Instructor by Scott Ritchie

Today we mainly covered three topics. We learned how to use the Interface Builder, putting elements on to it and etc. On the topic of Interface Builder, we also learned how to "ctrl + drag" elements in .xib files to and from the File Owner, setting up Outlets and Delegates.

We then moved on to how Objective-C would work without ARC. We learned that most of the time if we see an alloc, we basically would need to either release or autorelease. On a side note, this topic was by far the most confusing of them all.

The third topic we covered was how to work with Core Location and MapKit APIs. We created an app which found our current location and allowed us to put an annotation on the mapview.

Lastly, I learned today that you do not need a pointer to a struct. An example of this would be CLLocationCoordinate2D.

MVC - Model, View, Controller

Views - things you can see in the App

Views can be nested and can be a part of a hierarchy

Ex: UIButton

Controller - knows how to build and setup the view

Would probably not want to have lots of initializers

Model -

Would probably want lots of initializers

main.m

Contains a run loop

Stay the heck out of here

.xib files

XML Interface Builder

Shortcut

cmd + option + (1-4) - switch between attribute inspector

Interface Builder

“Files Owner” in .xib file

“ctrl + drag” = message from view controller to specific view (ex: UIButton)

“ctrl + drag” the way the message goes on runtime

IBAction - tells the interface builder this is a action that is available in the view controller

Target/Action: Target: whatever you drag to, Action: whatever you drag to

dot - is already implemented

dash - is implemented by someone else

IBOutlet - telling the .xib loading system to set value to something in the view

Connection Inspector - inspect the “Files Owner” to see all the connections or right click on the “Files Owner”

Initializers

***Important*** Page: 17 - Suggestions/Rules in iOS Programming Training Slides

A class can have zero or more initializers

One initializer is deemed “Designated”

All initializers call designated initializer

Designated initializer calls superclass’s designated initializer

Must override superclass’s designated initializer

More info: Chapter 2 (Page: 31) - Initializers in iOS Programming

Designated initializers

There is only 1 designated initializer in the class!!!

there is no way in Objective-C to tell ppl about what is the designated initializer

have “super” in it

Other initializers

they call the designated initializer with “self”

Without ARC:

Always turn on ARC! But… if you don’t turn it on below is what you need…

Note: You can turn off ARC on the file level

Without ARC, its all about pattern matching

- retain

Ups the retain count by 1

- release

Lowers the retain count by 1

- autorelease

Lower the retain count by 1… later

- dealloc

Cannot call this directly, call - release

only do stuff if you see one of the following within the same class:

new

alloc

retain

copy

Build -> Analyze to look at potential memory leaks

Core Location Delegation

Page 29 in iOS Programming Training Slides

Delegates and Protocol

CLLocationManager

setDistanceFilter

setDesiredAccuracy - the more accurate, the longer it will take to locate

setDelegate

startUpdatingLocation - this is non-blocking

CLLocation

In XCode, you can simulate the different locations

“#import” & “@import”

MapKit

First Responder

The keyboard, TextInputTrait

Bill did most of the work tonight showing how to get the sorcery gem installed to the project.  The students got to see a bit of the soft underbelly of how a non-trivial gem requiring some migrations and its own configuration can be a real time sink. While the gem itself was easy to install with bundler's Gemfile, the migrations were generated in an order that simply wouldn't work--the core migration that created the users table came out 4th of 4. A simple file rename put that straight. Getting to a working result took a bit of sleuthing.

First, we needed to have a Mailer defined because the optional modules for activation email and reset password were added and both need to send email. Bill used the rails generator to create the new UserMailer with two actions. The sorcery configuration is actually handled by an initializer so that was opened in redcar. Editing it looked easy since every option was shown with a comment that gave an example (typically the default) and the allowed/expected values.

What we hadn't counted on was the difficulty in actually getting things to work and finding a shortcoming in the mailer. To be fair, the mismatch between the UserMailer methods and the way the sorcery gem code tried to call them may have been due to our use of Rails 3.1.1, but the bigger problem was the fact that the code in an initializer is only run once. So… if you're in a console, don't bother trying to reload! and think all will be well. Oh, sure, some things start to work, but all the attempts to change the sorcery configuration are for naught until you remember to quit the console and restart it.

In any case, I think that it served to demonstrate (however unintentionally) the way a pair works. There were many suggestions that Bill and I threw out in the course of finally tracking down the issue with the UserMailer and ultimately the realization that the console needed to be restarted in order to pick up on the changes to the sorcery initializer file.

We ran out of time for the night before being able to actually run the code and send out an email for a created user account or to even begin the changes to the application that will use the new User model for authentication and tie an Instructor to a user. At the next session on Wednesday, we will be bringing some new code to the session and walking through it rather than coding it all live.