However, how does it choose which branch to run? It’s at this point where using a switch statement becomes handy. With functions, however, you can call them from multiple places when you needed to execute the same block of code instead. For example, let’s tell Swift we want an empty Int variable: If we run this code, we still see an error because integer variables can’t actually store nil. Thus, the condition equated to false, and it didn’t run our print statement inside the braces for that condition. You might do something like this: On line 2, we declared the variable sum and set it equal to 0. As a result of using the parameter, running the code above would print 7 to the console. But UIResponder in itself is a subclass of the NSObject which is described as “the root class of most Objective-C class from which subclasses inherit a basic interface to the runtime system and the ability to behave as Objective-C objects.” It’s basically what makes an object tick, if you will. If the status says that it is ready for you, Xcode is ready to accept your code and run it. Swift’s type-safety also prevents you from accidentally storing different kinds of data from what you intended in a variable. First, it checks that counter is indeed greater than 0, which is clearly true. Running this should print “Dog”, “Cat”, and “Bird”. Thus, I changed this definition of doing work by overriding doWork() in the Manager class. You’ve finally got a taste for how powerful subclassing can be. But for code that should run only while some condition is true, you would use a while loop. Keep in mind c and d are two separate Employee objects. What if we didn’t know how many elements myArray had? Recall that arrays could only store data of a specific type. The name of the book is “The Swift Programming Language – Swift 2 Edition”. If we wanted to print “Dog”, for example, we’d use index 0 in the brackets. After running the code above, we should get “I’m managing people” in the console because Swift is using the overridden method on line 4. In 2017 Swift was ranked as the 14th most favorable programming language by StackOverflow. I previously mentioned you can’t change the kind of data a variable stores, as in the following line: In Swift, there are several different types of data, but these are the most common ones: By no means are these the only data types in Swift. An equivalent way to write sum += counter is sum = sum + counter. Surprisingly, you can also completely omit parameter names and labels from the function call by using underscores as your argument labels. In the example above, I added a question mark after present followed by calling surprise. Notice the colon between the parameter name and data type. For our final chapters, we’ll learn about some “collection” data types that help us organize and manage collections of data. Well, that’s because the for loop starts with a clean slate on every iteration. What if we could actually tell it which two numbers to add? On line 8 below, we have an initializer with a String parameter, name, but with the basic initializer function above it as well: In this new initializer, I want to set our name property to the name input parameter that gets passed in. It’s very important to know this in advance, which is why we must specify this. Running this now prints out “a is greater than 15.”. The syntax for a range is number1...number2, which represents all numbers between number1 and number2. Variables a and b from above have simple data types, specifically Int and String. The empty array, , is similar to nil in that assigning a variable to  doesn’t help Swift determine the variable’s type. You don’t have to use var here; just add a stand-alone name. In this chapter, we’ll examine some basic math operations that you can use with constants, variables, and equations in general. How do we create more sophisticated conditions to check? Now you can see how powerful it is to use arrays with loops. Our demonstration above uses one level of subclassing or inheritance, but we can set up as many levels as we like: In the example above, we can declare another class called Person that contains the name property and have Employee inherit from Person. If you prefer to learn via video tutorials instead, check out the video version of this tutorial here. If we run the code again, we see that it will match the second case this time.
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