多态和动态绑定、多态和异常

@interface Car : NSObject
{
    @protected
    int cID;    //id
    @public
    NSString *name;     //名称
//    @private
    float speed;    //车速
}
- (void) run;
@end

@implementation Car
- (id) init
{
    if (self = [super init]) {
        cID = 1000;
        speed = 120;
        name = @"小汽车";
    }
    return self;
}
- (void) run {
    NSLog(@"start");
}
@end

//新建一个宝马汽车类,让他继承汽车类
@interface Bmw 

@end
@implementation Bmw
- (void) run 
{
    name = @"宝马";
    NSLog(@"car's name is %@", name);
}
@end
在main中测试
Car *car = nil;    //静态类型
car =  [[Car alloc] init];
[car run];

id car2;
car2 = car;

car->name = @"小车";    //公共的实例变量
// car->speed = 100;    //私有实例变量

Bmw *bmw = [[Bmw alloc] init];
[bmw run];

 

if ([audi isKindOfClass:[Car class]]) {
    NSLog(@"audi is a kind of Car");
}

if ([audi isMemberOfClass:[Car class]]) {
    NSLog(@"audi is a memberof Car");
}

if ([car isMemberOfClass:[Car class]]) {
    NSLog(@"car is a memberof Car");
}

//对象是否响应@selector指定的方法
if ([car RespondsToSelector:@selector:(run)]) {
    NSLog(@"car responds to run method");
}

SEL action;
action = @selector(run);
[car performSelector:action];
//等同于
// [car performSelector:@selector(run)];

//判断某个类是否是该类的子类
if ([Benz isSubClassOfClass:[Car class]]) {
    NSLog(@"benz is subclass of Car");
}

//判断两个对象是否是同一类型
if ( [Audi class] == [Benz class] ) {
    NSLog(@"audi and benz is the same class");
}

//OC的异常处理
@try {
    [car noSuchMethod];
}
@catch (NSException *exception) {
    NSLog(@"catch exception %@ %@",     [exception name], [exception reason] );
//编写代码，记录这个日志
}
@finally {
       //...
}