Programming for Non-Programmers: iOS 7
Illustration by Don Barnett

Solution: Create two variables


From:

Programming for Non-Programmers: iOS 7

with Todd Perkins

Video: Solution: Create two variables

There are multiple ways you could have approached this challenge. And as long as you arrive at the Here is the method that I used. So, there is one. And there is another label.
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  1. 5m 18s
    1. Welcome
      44s
    2. What you should know before starting this course
      1m 17s
    3. Related courses
      1m 8s
    4. Using the exercise files
      1m 19s
    5. Viewing the finished app
      50s
  2. 10m 24s
    1. Finding and installing Xcode
      35s
    2. Creating an Xcode project
      1m 55s
    3. Understanding the Xcode interface
      3m 54s
    4. Configuring Xcode for app development
      2m 14s
    5. Configuring the iOS Simulator for app development
      1m 46s
  3. 43m 43s
    1. Understanding how programming works
      2m 34s
    2. Understanding variables
      2m 56s
    3. Using primitive variables
      9m 10s
    4. Using pointer variables
      4m 51s
    5. Using instance variables
      5m 19s
    6. Connecting visual objects to variables
      8m 12s
    7. Placing a number variable in a string
      4m 33s
    8. Challenge: Create two variables
      54s
    9. Solution: Create two variables
      5m 14s
  4. 27m 14s
    1. Understanding functions, methods, and selectors
      4m 43s
    2. Using functions, methods, and selectors
      7m 1s
    3. Understanding parameter functions
      2m 10s
    4. Connecting a button to a function
      7m 47s
    5. Challenge: Create a counter app
      43s
    6. Solution: Create a counter app
      4m 50s
  5. 13m 38s
    1. Understanding conditional statements
      2m 35s
    2. Using conditional statements
      5m 21s
    3. Challenge: Build an on/off button app
      39s
    4. Solution: Build an on/off button app
      5m 3s
  6. 44m 59s
    1. Viewing the app's code structure
      2m 11s
    2. Setting up the user interface
      7m 9s
    3. Setting up variables and functions
      5m 8s
    4. Connecting all of the visual elements to code
      2m 59s
    5. Displaying tapped numbers in the calculator
      4m 47s
    6. Controlling when tapped numbers should not appear in the calculator
      3m 27s
    7. Making the Clear button clear all values
      1m 4s
    8. Setting the calculator to add or subtract
      4m 29s
    9. Showing the total when the equals button is tapped
      3m 40s
    10. Formatting a number with commas
      5m 25s
    11. Challenge: Add a multiplication button
      1m 5s
    12. Solution: Add a multiplication button
      3m 35s
  7. 24s
    1. Next steps
      24s

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Watch the Online Video Course Programming for Non-Programmers: iOS 7
2h 25m Beginner Apr 10, 2014

Viewers: in countries Watching now:

iOS app development is actually simpler than you might think—even if you're not an experienced programmer. In this course, Todd Perkins bundles the most important concepts in iOS into a quick course, explaining the development process in a visual way that people of any background can understand. No programming experience required! At the end, you'll have a finished app and a basic understanding of Xcode, the toolset for developing iOS apps; building blocks like variables, functions, and conditional statements; and interface design. You can also figure out if an iOS learning path is right for you, without a lengthy time commitment.

If you find you'd like to learn more, see iOS App Development Essential Training, Foundations of Programming: Fundamentals, or any of the other programming courses in our library.

Topics include:
  • Installing Xcode
  • Creating an Xcode project
  • Configuring the iOS Simulator
  • Understanding variables
  • Connecting visual objects to variables
  • Understanding functions, methods, and selectors
  • Connecting a button to a function
  • Using conditional statements
  • Setting up the user interface
  • Connecting code elements to build an app
Subject:
Developer
Software:
iOS
Author:
Todd Perkins

Solution: Create two variables

There are multiple ways you could have approached this challenge. And as long as you arrive at the correct solution, any method you use can be correct. Here is the method that I used. In mainstoryboard.storyboard, I made sure that my utility view was showing, and then I clicked and dragged two labels onto the screen. So, there is one. And there is another label. Then, I created two variables, one for each label.

I did that in ViewController.h. At the end of line 11, I will go to the next line, create an open curly brace and type enter. And now I'm going to create an IBOutlet that is a UI label called name. At this point, we need two different UI labels. I'm going to show you a short cut to doing that. One way is, we can select this line and copy with Cmd+C. Go to the next line, paste the code with Cmd+V, and change name to age.

But since there are two variables that are the same data type, that is IBOutlet, UILabel. We actually have a short cut. I'll show you how to do that. Going to delete that line of code. And after name and before the semi colon. I'm going to type a comma, asterisk and then age. This is the same as the two line code method I used. It's just a short hand way for writing the same thing. So, here I've created two variables. One called name. And one called age.

Of course, I didn't expect you to know that going in, I just wanted to show you a shorthand technique for creating multiple variables of the same type. Back to mainstoryboard.storyboard. Now I need to connect my labels to my code. Remember, you click on View Controller on the left side, and that's under View Controller Scene, so you might have to expand that, and then click on the code connections button, which is all the way on the right. It's a circle with an arrow inside of it. And then, under Outlets, you should see age and name.

So, I'm going to click and drag from this circle for age onto the bottom label. And then for name, I'm going to click and drag from the circle to the top label. With those code connections made, I'm going to save the file. Now, I'll go over to viewController.m. And as usual, I'm going to hide the utility view because I no longer need it. In viewdidload, right below the comment, I'm going to type name.text, and I'm going to set that equal to an NSString, which is an at symbol with quotes.

Don't forget the semicolon at the end of the line. Now, I'll type my name inside of the string. So, I put Todd in there, and then I'll go to the next line. So that one was really easy. The hard part is putting a number inside the text field. But there is a cheating way to do that. If I type age.text, I can just set it equal to the NSString in quotes. Zero, of course, because my age is a secret. So, instead of using the variable, you could have just typed the number of your age inside of the string. And that is a fine solution.

There's nothing wrong with using that method. So, when I test this in the simulator, you'll see Todd and zero. But let's say you wanted to use a number variable. Right below name.text, I'm going to create an integer called myAge, and I'm using camel case, so the A is capitalized, equals, and let's say 100 here. Again, semicolon to end the statement. And I want to put that age variable inside of the text field. Remember, you can do that by using the command NSString, string with format. So, I'm going to delete the @ in the quotes and the zero on the line 23 in my code, I'm going to type an open and close square bracket.

And inside of the square brackets, NSString. Now, I'm using the code hinting by pressing Return, string with format. Again, I'm pressing Return. Having Xcode write that for me. This makes sure I don't type it incorrectly and saves time. So, remember, here, we're going to type this blank string first. That is an at symbol with quotes. And now, we're going to put, inside of the quotes, the placeholder for an integer variable which is %i. After the close quote, type a comma, and then the name of your variable, which in this case, is my age.

Now, when we test the app in the simulator, we'll see Todd, and 100. Again, however you approach this challenge, as long as you get your name and age in the text fields, and you used code to get it in there, it's correct. But, hopefully, you learned something new in this process.

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