How do you declare a block in Objective-C?

How Do I Declare A Block in Objective-C?

1. As a local variable: returnType (^blockName)(parameterTypes) = ^returnType(parameters) {…};
2. As a property:
3. As a method parameter:
4. As an argument to a method call:
5. As a parameter to a C function:
6. As a typedef:

What is block syntax in Objective-C?

An Objective-C class defines an object that combines data with related behavior. Blocks are a language-level feature added to C, Objective-C and C++, which allow you to create distinct segments of code that can be passed around to methods or functions as if they were values.

What is property in Objective-C?

Properties in Objective-C are used to store data in instances of classes. They define memory management, type, and access attributes of the values they store such as strong , weak , assign , readonly , readwrite , etc. strong , weak , assign property attributes define how memory for that property will be managed.

What is enum Objective-C?

enum , or enumerated value types, are the C way to define constants for fixed values, like days of the week, or available styles of table view cells. In an enum declaration, constants without explicit values will automatically be assigned values sequentially, starting from 0 .

Where do we declare enum in Objective-C?

If you want to use this myTypes enum somewhere in your code on other class, then you have to import the MyFirstClass. h in that class directly or indirectly. So the visibility of enum is, where it was defined. If u want to use the enum in all the class that u have then just create the seperate EnumConstants.

What do you mean by Objective C blocks?

Objective-C Blocks. An Objective-C class defines an object that combines data with related behavior. Sometimes, it makes sense just to represent a single task or unit of behavior, rather than a collection of methods.

What is the syntax of an Objective C program?

Objective-C Basic Syntax. You have seen a basic structure of Objective-C program, so it will be easy to understand other basic building blocks of the Objective-C programming language. Tokens in Objective-C. A Objective-C program consists of various tokens and a token is either a keyword, an identifier, a constant, a string literal, or a symbol.

Why are retain cycles dangerous in Objective C?

Retain cycles are somewhat dangerous with blocks. You may have seen this warning: The reason is that someBlock is strongly held by self and the block will “capture” and retain self when/if the block is copied to the heap. The safer, but loquacious workaround is to use a weakSelf:

When to use retain or copy in Objective C?

In Objective C, you have the usual retain, copy, release and autorelease methods. The nuance is that most of the time, in Objective C you want to use copy instead of retain. When blocks are created, like most variables, they live on the stack.