CODEWITHSUNDEEP
swiftglobal-variables
user5430804
user5430804

Reputation: 1

In swift，is it a global variable or property?

Global variables are variables that are defined outside of any function, method, closure, or type context.《The Swift programming Guide》。

So this is a question：

class Dog {
    var name: String?
    func run(){

    }
}

name is a global variable or property?

@implementation Dog{

 NSString *name;
- (void)run{ 

   }
}

name is a global variable or property?

Upvotes: 0

Views: 186

Answers (2)

Jesper
Jesper

Reputation: 7605

Since a class is a type, name is a property in the Swift example.

In the Objective-C example, name is a global variable since properties are defined in the @interface scope and requires a @property declaration. (Instance variables don't require any declaration but they have to be inside a block inside the @interface or @implementation scopes.)

Upvotes: 2

Rob Napier
Rob Napier

Reputation: 299275

name is inside a type context, class Dog, so it is a property of Dog instances.

The second example is similar to Objective-C (it definitely isn't Swift), but it's incorrect ObjC syntax. It's not clear what the actual code is. If you meant:

@implementation Dog 
NSString *name;
- (void)run {     
}
@end

then name is a global, but should never write it that way. It's very confusing. The name declaration should go outside the @implementation block to avoid confusion. If, on the other hand, you meant to write:

@implementation Dog {   
    NSString *name;
}

- (void)run {
}
@end

Then name is a private instance variable (which is not the same thing as a property). This is an unusual syntax in modern ObjC and should generally be avoided.

Upvotes: 1

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