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+--- Thread: import Swift vs import Foundation (/Thread-import-Swift-vs-import-Foundation)
import Swift vs import Foundation - Mrboroughenglish2 - 07-18-2023
**Question**
What is the difference between `import Swift` and `import Foundation`?
Until I read [this comment][1] by [Martin R][2], I didn't even know that there was an `import Swift`.
**Reading**
I couldn't find the documentation and doing a Google search didn't turn up much.
**What I tried**
Testing it out shows that `import Swift` does not give any compile errors, but that doesn't really answer my question.
If I were to guess, I would say that you import Swift for Swift projects and that you import Foundation for Objective-C projects or maybe for Swift projects that use Objective-C classes (like `NSString`).
Testing this in the Playground:
import Foundation
import Swift
var str = "Hello, playground"
let str2: NSString = "hello"
let str3: String = "hello"
Commenting out `import Swift` gives no errors and `str` is of `String` type. However, commenting out `import Foundation` gives an "undeclared type" error for `NSString`.
**My question revisited**
I would be happy enough to abandon Foundation and just use Swift. So am I right to just import Swift all the time unless I specifically need to use one of the old Objective-C classes?
[1]:
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RE: import Swift vs import Foundation - montefid - 07-18-2023
*import Foundation* used for access NSObject or one of its sub class.NSObject means we can extend our class using *objective C* runtime features.But import UIKit or import swift, that is automatically generate while we create our xcode project
RE: import Swift vs import Foundation - unchoosable199237 - 07-18-2023
If you want to work with Strings, Dates, etc you need to import Foundation.
**The Foundation framework provides a base layer of functionality for apps and frameworks, including data storage and persistence, text processing, date and time calculations, sorting and filtering, and networking.**
If you want to work with UITableViewController, UIAlertController you need to import UIKit.
**If you import UIKit you do not need to import Foundation because it already imports it in the backstage.**
The Swift standard library defines a base layer of functionality for writing Swift programs, including:
Fundamental data types, Common data structures, Global functions such as print(_:separator:terminator:) and abs(_:), Protocols, such as Collection and Equatable... etc
**If you import Foundation, then no need to import Swift again as Foundation contains references to Swift Standard Library by default.**
**When you are writing something not for iOS Apps, like say a server programming based on Vapor , you may need to consider import Swift.**
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RE: import Swift vs import Foundation - hydroponics201 - 07-18-2023
Yes, you will only need `import Foundation` if you want to access NSObject or one of its subclasses. Foundation is the framework that brings in that class hierarchy. However, it's highly likely that in a project you'll need more than just `import Swift`. Like Rob commented, `import UIKit` is also a nice option.
In case you haven't read it already, Apple explains the Foundation framework [here][1].
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