What is a selector in Objective-C?
In Objective-C, selector has two meanings. It can be used to refer simply to the name of a method when it’s used in a source-code message to an object. It also, though, refers to the unique identifier that replaces the name when the source code is compiled. Compiled selectors are of type SEL .
What is the use of selector in Swift?
Use Selectors to Arrange Calls to Objective-C Methods In Objective-C, a selector is a type that refers to the name of an Objective-C method. In Swift, Objective-C selectors are represented by the Selector structure, and you create them using the #selector expression.
What is dynamic dispatch and how does it work in Objective-C?
Dynamic dispatch, for example, is one of the features that make Objective-C as dynamic as it is. Dynamic what? 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.
What is selector and descriptor?
The selector, located in the segment register, selects one of 8192 descriptors from one of two tables of descriptors. The descriptor describes the location, length, and access rights of the segment of memory. Indirectly, the segment register still selects a memory segment, but not directly as in the real mode.
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. A selector by itself doesn’t do anything. It simply identifies a method.
What is method Swizzling Swift?
iOS Swift Tips. Swizzling (other languages call this “monkey patching”) is the process of replacing a certain functionality or adding custom code before the original code is called. For example, you could swizzle UIViewController.
What is static and dynamic dispatch?
Static dispatch (or early binding) happens when I know at compile time which function body will be executed when I call a method. In contrast, dynamic dispatch (or run-time dispatch or virtual method call or late binding) happens when I defer that decision to run time.
What is dynamic dispatch method?
Dynamic method dispatch is the mechanism by which a call to an overridden method is resolved at run time, rather than compile time.
What are selectors and types of selectors explain with examples?
All CSS Simple Selectors
| Selector | Example | Example description |
|---|---|---|
| #id | #firstname | Selects the element with id=”firstname” |
| .class | .intro | Selects all elements with class=”intro” |
| element.class | p.intro | Selects only
elements with class=”intro” |
| * | * | Selects all elements |
What is the use of segment selector?
A segment selector provides the software that uses it with an index into the GDT or LDT (the offset of its associated segment descriptor), a global/local flag (determines whether the selector points to the GDT or the LDT), and access rights information.”
What are selectors in iOS?
Why method swizzling is used?
Method swizzling is the process of replacing the implementation of a function at runtime. Swift, as a static, strongly typed language, did not previously have any built-in mechanism that would allow to dynamically change the implementation of a function.
What is a difference between NSArray and NSSet?
An NSSet is much like an NSArray, the only difference is that the objects it holds are not ordered. So when you retrieve them they may come back in any random order, based on how easy it is for the system to retrieve them.
What is static method dispatch?
In computing, static dispatch is a form of polymorphism fully resolved during compile time. It is a form of method dispatch, which describes how a language or environment will select which implementation of a method or function to use.