I´m using a struct on Objective-C to store some data, something like this:
@interface Interface : NSObject
{
// my Data
struct Data
{
__unsafe_unretained BOOL isInit;
__unsafe_unretained BOOL isRegister;
__unsafe_unretained NSString* myValue;
// Data() : isInit(false), isRegister(false), myValue(@"mYv4lue") {} // Constructor doesnt work
};
struct Data myData; // Create Struct
}
But I can't compile with a constructor. I want the values take some default value when I create the struct.
How can I do this?
For instance, with this struct: struct Point { int x; int y; int z; }; We can initialize an instance with the following syntax: Point p = {1, 2, 3};
Initializing Structures The fastest way to initialize a structure is to enclose the values in a pair of braces: Date today = {5, 22, 2011}; You can list fewer values, and they will be filled in until the end of the values you list. The remaining values will be undefined.
When initializing an object of struct or union type, the initializer must be a non-empty, (until C23) brace-enclosed, comma-separated list of initializers for the members: = { expression , ... }
3. Constructor creation in structure: Structures in C cannot have a constructor inside a structure but Structures in C++ can have Constructor creation.
What is Constructors and Creating Objects in Objective C ! Constructor/initializer is a method which we call while creating a new object in Object Oriented Programming. In this method we write all the code related to initial setup of an object. Objective C have a default construction called init which is present in its root class NSObject.
If it's global, you first need to create the object and then initialize it: class my_class { my_struct * s1; my_class () : s1 (new my_struct ()) { s1->i = 10; s1->name = "anyname"; } }; Show activity on this post.
In the same way, a constructor is a special method, which is automatically called when an object is declared for the class, in an object-oriented programming language. So, combining these two different methodologies, we can say that when these constructors are defined inside a Struct, then these would be referred to as Struct constructors.
Objective-C Lesson 11: Object Initialization 1 Allocation. Creating a new object in Objective-C is usually a two-step process. ... 2 Convenience Initializer. Most classes also have convenience initializers, which take arguments with which to set the ivars. ... 3 Constructors. ...
You could initialize a struct as follows using static object for default settings.
typedef struct
{
BOOL isInit;
BOOL isRegister;
__unsafe_unretained NSString* myValue;
} Data;
static Data dataInit = { .isInit = NO, .isRegister = NO, .myValue = @"mYv4lue"};
Data myCopyOfDataInitialized = dataInit;
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