Are these two instancetype initialization methods equal?

Question

I was wondering are these two equal:

A single parentheses inside the if statement:

- (instancetype)init {
    
    if (self = [super init]) {
        
        // ...
    }
    
    return self;
}

Double parentheses inside the if statement:

- (instancetype)init {
    
    if ((self = [super init])) {
        
        // ...
    }
    
    return self;
}

Answer 1

Yes,...... as it only depends on the the expression being compared no matter how many parentheses exists (that should be even)

Parentheses help compiler understand the expressions with prioritization , if statement in objective c needs at least one () while adding more will work also but it's useless

Answer 2

They are the same, in that they mean the same thing and produce the same code, however the compiler will behave a little differently.

In C like languages an easy typing mistake that is visually hard to spot is to enter =, that is assignment, when ==, that is equality, is intended. This error can produce very different results and hard to spot bugs. E.g.:

if (a == b) { ... }

tests whether a and b have the same value and if so the statements in the if are executed. However:

if (a = b) { ... }

assigns the value in b to a and then executes the statements if the value of a and b (they have the same value due to the assignment) is non-zero. Clearly the two behaviours are quite different.

To help out if the compiler sees a single = in an if it will issue a warning so the programmer is alerted to the possibility of a typo. The warning will be omitted if double parentheses are used:

if ((a = b)) { ... }

which is why you'll see this pattern in code. HTH

Answer 3

Yes, they are equal.

self is getting the reference that it needs to store after [super init] call. Both of these do the same thing.