CODEWITHSUNDEEP
xcodeuitableviewswift
Edward Potter
Edward Potter

Reputation: 3820

In Swift, what is the difference between the two different usages of self?

In this Swift Xcode 6.0.1 example for a table cell, .self is used as a suffix (don't remember seeing self used like that before), and a prefix self. (which of course is everywhere), trying to understand what that really means. 

// Register the UITableViewCell class with the tableView

self.tableView.registerClass(UITableViewCell.self, forCellReuseIdentifier: self.cellIdentifier)

Upvotes: 6

Views: 867

Answers (3)

Alex Wayne
Alex Wayne

Reputation: 187014

I think it's because everywhere else the type is used to type some variable. But SomeType.self says to use this type as the value. I don't think a type can stand on it's own, unless you call .self.

Try the following in a playground.

class Foo {}
Foo // ^ Compiler error: expected member name or constructor call after type name

But with .self

class Foo {}
Foo.self // console reports: (Metatype)

Upvotes: 3

ColinE
ColinE

Reputation: 70122

Your first usage of self as a prefix is a reference to the instance of the class that contains the method that is currently being invoked. In the second usage, self is referring to a type as a value, in this case UITableViewCell.self refers to the UITableViewCell type

Upvotes: 8

mipadi
mipadi

Reputation: 410622

self is a method that returns the receiver of the message. In this case, it returns the Class object for UITableViewCell.

Upvotes: 3

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