Quick Answer: What Does @Objc Mean In Swift?

What is @discardableResult in Swift?

The @discardableResult attribute allows us to enable both cases without having to deal with annoying warnings or underscore replacements.

It’s a small feature in Swift but it’s something you wish you knew once you get to know it..

What is thread safe in Swift?

Thread safe is a concept in the context of multi-thread and it means any shared data is accessed by only one thread at any given time. If you want to write/read access to a shared resource from different threads, you should take the thread safety into consideration.

What is dynamic in Swift?

Dynamic dispatch. It simply means that the Objective-C runtime decides at runtime which implementation of a particular method or function it needs to invoke. … Swift uses the Swift runtime whenever possible. The result is that it can make a number of optimizations.

Does Swift have a runtime?

The Swift runtime can be more deeply integrated and optimized with these host operating systems, allowing Swift programs to launch faster, get better runtime performance, and use less memory.

What is IOS selector?

A selector is the name used to select a method to execute for an object, or the unique identifier that replaces the name when the source code is compiled. The selector could be used with an instance of each of the classes to invoke its run method—even though the implementation might be different for each. …

Are Swift arrays thread safe?

A code is called “Thread safe” if any shared data is accessed by only one thread at any given time. Notice these shared data are called critical sections in an operating system. The point is Swift collection types like Array and Dictionary are not thread-safe when declared mutable (With var keyword).

What is DispatchQueue main async in Swift?

DispatchQueue. main (the main queue) is a serial queue. … It doesn’t block the queue. From Stack Overflow. Essentially this just means that sync will block the main thread until the task has finished, async means this will happen on a background thread and update the main thread when it is finished.

What is Inlinable in Swift?

Introduced in Swift 4.2, the @inlinable attribute allows you to enable cross-module inlining for a particular method. When this is done, the implementation of the method will be exposed as part of the module’s public interface, allowing the compiler to further optimize calls made from different modules.

Is swift dynamic or static?

But Swift itself is static, and in fact is explicitly designed in order to minimize or eliminate the use of Objective-C-type dynamism. Swift itself, is statically typed. When used with Cocoa, you get access to the objective-c runtime library which gives you the ability to use dynamic classes, messages and all.

What is Dispatch in Swift?

Method Dispatch is how a program selects which instructions to execute when invoking a method. It’s something that happens every time a method is called, and not something that you tend to think a lot about.

What is observer in Swift?

Observer is a behavioral design pattern that allows some objects to notify other objects about changes in their state. The Observer pattern provides a way to subscribe and unsubscribe to and from these events for any object that implements a subscriber interface.

What is attribute in Swift?

There are two kinds of attributes in Swift—those that apply to declarations and those that apply to types. For example, the discardableResult attribute on a function declaration indicates that, although the function returns a value, the compiler shouldn’t generate a warning if the return value is unused. …

What is #selector Swift?

Selectors are effectively the names of methods on an object or struct, and they are used to execute some code at runtime. They were common in Objective-C, but the earliest versions of Swift didn’t include some core selector functionality so their use declined for a while.

Why is swift type-safe?

You can use a tuple to return multiple values from a function as a single compound value. … Swift is a type-safe language, which means the language helps you to be clear about the types of values your code can work with. If part of your code requires a String , type safety prevents you from passing it an Int by mistake.

What is the difference between Swift 4 and 5?

Swift 5 is source compatible with Swift 4.2, but isn’t binary compatible with earlier Swift releases. However, future releases will be binary compatible with Swift 5 thanks to ABI stability. … You’ll find Swift Evolution proposal numbers like [SE-0001] in each section of the tutorial.

Is Swift a typed language?

Swift is a type-safe language. All variables have a declared type. All functions/methods have a type-signature which declares the types of its arguments and the type of what it returns. The Swift compiler checks at compile time that all your types match up and your program won’t compile if they don’t.

What is @objcMembers?

Applying the @objcMembers attribute to a class implicitly adds the @objc attribute to all of its Objective-C compatible members. … The class is a part of your Swift framework that is used in some other Obj-c project as a dependency.