InitWithCoder，[super init]还是[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) {
        ...

Answer 1

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.

Answer 2

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

[super initWithCoder:decoder]

Otherwise call its designated initializer.