When reading Objective C code declarations, keep the viewDidLoad handy. Often the assignment happens in the viewDidLoad method of your. In Objective C, you declare in one place and assign in another. Swift encourages assignment of values to variables and constants at declaration. Next comes the identifier myPicker with the class UIPickerView as an optional. The outlet is merely We have a weak variable so next we have weak var. If you never saw the difference between the two languages, you might begin to see why Swift is so speedy for coding. This translates in Swift weak var myPicker: UIPickerView!
It’s a good idea to their Swift equivalent an optional value. Pointers in Objective C can have nil values. the asterisk ( *) means this is a pointer, which is true of most object identifiers in Objective C. Finally, we have the identifier for the property *myPicker. Next we have the class of the identifier, UIPickerView. Since Swift has an even more automatic version of Automatic Reference Counting(ARC) than Objective C, we ignore the nonatomic part. (weak, nonatomic) IBOutlet sets an outlet with a weak variable. Let’s dissect this outlet from a Swift perspective. We have one of these as an outlet to our picker (weak, nonatomic) IBOutlet UIPickerView *myPicker
#import ViewController : (weak, nonatomic) IBOutlet UIPickerView NSInteger the header file, you will find a series of tags beginning with You’ll find on each property a tag. In the code I found the header looks like this: You will repeat all your methods and target actions in the implementation file when you write the code for it. The header file has no code though: it is only declarations. It is in the header file that you find most of the class definition. h file includes properties, methods target-actions, outlets, and often protocols for delegates. Anything private and not shared gets declared in the other file, the implementation file. h file has information that is public in scope. One of those two files in Objective C is a header file or. Scope rules are very different between the two languages. We refer to how much something shares as its scope. Some data is shared in a class, some isn’t. Objective C uses two files for a class, unlike Swift’s single file for a class. We’ll discuss some things you should know and try an example of converting a method for a UIPickerView from Objective C into Swift. I’ve wanted to write a piece on converting from Objective C to Swift for a while. Of course it was in Objective C, not Swift. I did a little web searching and I did find a solution. The reader found some code in Objective C that did that.
When asked, I did not know how to do this. The UIPickerView does not have this ability. If you are familiar with the date picker it goes from 0 to 59 and then loops back to 0, making a continuous wheel. I had a case of that this week when a reader asked me about continuous picker view wheels. Sometimes you have some Objective C code and want to make it into Swift code.