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Understanding parameter functions


From:

Programming for Non-Programmers: iOS 7

with Todd Perkins

Video: Understanding parameter functions

In addition to the standard functions that we've seen so far, there are more complex functions called parameter functions. So, what are parameter functions? Parameter functions are a way for functions to have more versatility. What that means is that you can provide different input for the same function. In other words, you can perform the same process with different input. In a parameter function, input is called a parameter, and it's a lot like a variable. So, what does a parameter function look like when you create it? You add a colon after the function name, the received data type is in parentheses, that's the input for the function.
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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 thinkā€”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

Understanding parameter functions

In addition to the standard functions that we've seen so far, there are more complex functions called parameter functions. So, what are parameter functions? Parameter functions are a way for functions to have more versatility. What that means is that you can provide different input for the same function. In other words, you can perform the same process with different input. In a parameter function, input is called a parameter, and it's a lot like a variable. So, what does a parameter function look like when you create it? You add a colon after the function name, the received data type is in parentheses, that's the input for the function.

The received data variable, or again, parameter name. And finally, when executed, the function uses a colon and then the value after the name of the function. So, let's look at an example in actual code of what a parameter function looks like. Think of exercising. You have the concept of exercising, and that would be the function of exercising. But every time you exercise, you don't necessarily exercise for the exact same amount of time. So if you had an app that was tracking the number of minutes that you exercised, then you could send it, whether you exercised for 30 minutes or 60 minutes.

And the exercise function could then add up your total amount of exercise based on the number that's passed in. So the top two lines are executing the exercise function, passing in values of 30 and 60, respectively. The exercise function receives that integer value as the number of minutes parameter. Within the function, number of minutes can be used like a variable that's known only to the exercise function. And again, this reduces redundancy in code, because we can use the same function and have different input.

And so, if you wanted to keep track of the amount of exercise over a period of time, you add to it in the amount that's passed in through number of minutes. And just like regular functions, parameter functions have the same rules. Start with a lowercase letter. Only use letters, numbers, and underscores. Use camelCase. And don't use any reserved words.

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