啦啦啦, 我们继续复习iOS Objective-C的知识. 今天是Objective-C的大头—-Runtime. Runtime可以说是Objective-C最难,也是最有趣的部分了. 理解好Runtime对日常开发可以说是如虎添翼. 所以面试中Runtime也是最经常被问到的知识点.
废话不多说, 黑喂狗!
Objective-C Runtime Q&A
Q: Why do we say Objective-C is dynamic language? What is Objective-C Runtime?
A: Objective-c is based on C but with additional OOP features. Additionally, unlike C being a static language whose function invocation is fixed at compiling and linking time, a lot of such decision are delayed to runtime. The primary mechanism of achieving such goal is called Messaging.
Objective-C Runtime is a set of API that is written by C, C++ and Assemble, whose purpose is to add OOP capability to OC and messaging mechanism.
Q: Explain Runtime messaging process? When will there be unrecognized selector Exception?
A: TODO
Follow up: Give me a usecase of it
A: TODO
Q: How Object is implemented in ObjC?
A: TODO
Q: Do you know isa pointer? What is it used for?
A: TODO
Follow up: Explain to me what will happen if we call [[NSArray array] count]?
A: TODO
Follow up: How about [NSArray array]?
A: TODO
Follow up: Speed up the look up?
A: TODO
Q: What is SEL and IMP? How they are used?
A: TODO
Q: What is class_rw_t and class_ro_t?
A: TODO
Q: Can we add instance variable at runtime?
A: TODO
Follow up: What can we do to add iVar at runtime?
A: TODO
Follow up: Give me a usecase of it
A: TODO
Follow up: When do we need to dealloc associated objects?
A: TODO
Q: What is the output of the following program?
```
@implementation Son : NSObject
- (id)init
{
self = [super init];
if (self) {
NSLog(@"%@", NSStringFromClass([self class]));
NSLog(@"%@", NSStringFromClass([super class]));
}
return self;
}
@end
```A: TODO
Q: What is Method Swizzling?
A: TODO
Follow up: Give me a usecase of it.
A: TODO
Q: NSObject +load and +initialize - What do they do?
A: TODO