ios - Objective-C 调用特定的类方法

Question

我有一个在初始化器中有这个的类:

@implementation BaseFooClass

-(id) init
{
     if (self = [super init])
     {
          // initialize instance variables that always need to start with this value
     }

     return self;
}

-(id) initWithSomeInt:(int) someInt
{
     if (self = [self init]) // <-- I need to make sure that I am calling BaseFooClass's init here, not SubFooClass's, does that make sense?
     {
          self.someInt = someInt;
     }

     return self;
}

@end

一切都很好，花花公子。我的问题是当我实现子类时:

@implementation SubFooClass

-(id) init
{
     return [self initWithSomeInt:0];
}

-(id) initWithSomeInt:(int) someInt
{

     if (self = [super init]) // <--- Infinite loop (stack overflow :) )
     {
          // initialize other variables
     }
}

@end

我基本上需要专门调用 BaseFooClass 的 init 而不是 SubFooClass 的 init。

我无法更改对象的初始化方式，因为我正在将项目从 C# 转换为在我的 iPad 应用程序中使用。

先谢谢大家

编辑:

由于有人问，这是我的标题:

@interface BaseFooClass : NSObject

// implicit from NSObject
// -(id) init;

-(id) initWithSomeInt:(int) someInt;

// more methods

@end

@interface SubFooClass : BaseFooClass

// implicit from NSObject
// -(id) init;

// implicit from BaseFooClass
//-(id) initWithSomeInt:(int) someInt;


@end

Answer 1

由于运行时将方法转换为函数调用的方式，Objective-C 无法以这种方式工作。 Self 始终是分配类的实例，即使在调用父类(super class)的方法时也是如此。您需要为您的 BaseClassFoo 创建指定的初始值设定项并始终去那里。所以你应该这样做:

@implementation BaseFooClass

-(id) init
{
  return [self initWithSomeInt:0]; // redirect super class's designated initializer
}

-(id) initWithSomeInt:(int) someInt
{
  if ((self = [super init])) // Designated initializer always calls into super class's designated initializer (in this case, NSObject's designated initializer is init
  {
    self.someInt = someInt;
  }

  return self;
}

@end

@implementation SubFooClass

// Here we don't override init because our super class's designated initializer
// is initWithSomeInt:
// -(id) init
// {
//   return [self initWithSomeInt:0];
// }

// we override this because it's our superclass's designated initializer, plus it
// is ours as well
-(id) initWithSomeInt:(int) someInt
{
  if ((self = [super initWithSomeInt:someInt]))
  {
    // initialize other sub-class specific variables
  }
}

@end