InitWithCoder, [super init] or [super initWithCoder]?

Question

Can I ask which version I should be using, in my older apps I seem to be using "B" but when I look at a lot of examples online I am seeing a lot of versions that look like "A".

// A
- (id)initWithCoder:(NSCoder *)decoder {
    self=[super initWithCoder:decoder];
    if(self) {
        ...

OR

// B
- (id)initWithCoder:(NSCoder *)decoder {
    self=[super init];
    if(self) {
        ...

albertamg · Accepted Answer · 2011-07-25 18:29:20Z

13

Depends on whether the superclass conforms to the NSCoding protocol or not. If it does, you must call [super initWithCoder:decoder]. If it does not, you must call the superclass' designated initializer.

For example, if your class is a direct subclass of NSObject, you would call [super init], NSObject's designated initializer, since NSObject does not conform to the NSCoding protocol.

edited Jul 25, 2011 at 18:29

answered Jul 25, 2011 at 18:14

albertamg

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3 Comments

fuzzygoat Over a year ago

Can I ask, if a class conforms to NSCoding does initWithCoder become its designated initialiser?

albertamg Over a year ago

No, the designated initializer remains the same.

jogloran Over a year ago

The Xcode 4 boilerplate for initWithCoder uses [super initWithCoder] regardless of whether the superclass conforms to NSCoding -- took a little while to figure out where it was blowing up.

BoltClock · Accepted Answer · 2011-07-25 18:39:24Z

12

If the superclass adopts NSCoding (which is likely albeit not always the case), always call

[super initWithCoder:decoder]

Otherwise call its designated initializer.

edited Jul 25, 2011 at 18:39

answered Jul 25, 2011 at 18:11

BoltClock

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2 Comments

fuzzygoat Over a year ago

Ah I see, the superclass is NSObject (which from what I can tell does not conform to NSCoding) so in this case I should use "B". Much appreciated, a very clear / concise answer.

slboat Over a year ago

NSObject is don't like init withCoder,aha:)

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