我有一个类在初始化器中有这个:
@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
这一切都很好。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。
先谢谢大家了
编辑:
由于有人询问,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
最佳答案
Objective-C 不会以这种方式工作,因为运行时将方法转换为函数调用的方式。 Self 始终是分配的类的实例,即使在调用父类(super class)的方法时也是如此。您需要为 BaseClassFoo 创建指定的初始值设定项并始终转到那里。所以你应该做这样的事情:
@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
关于ios - Objective-C调用特定类方法,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/3881477/