1.@property 是什么？    @perperty 是声明属性的语法，他可以快速方便的为实例变量创建存取器，并允许我们通过点语法使用存取器    【存取器：用于获取和设置实例变量的方法，获取实例变量值得是getter，设置实例变量存取器的是setter】    2.手工创建存取器        #import 
     
          @interface Car : NSObject    {        NSString *carName;        NSString *carType;    }    @property(nonatomic,strong) NSString *carName;    @property(nonatomic,strong) NSString *carType;    @property(nonatomic,strong) NSString *carNum;    @end    上面的carName和carType就是类Car的属性变量，可以看到分别对这两个实例变量声明了get/set方法，即存取器        #import "Car.h"    @implementation Car    @synthesize carName;    @synthesize carType;    @end    以上代码对存取器进行了实现        #import 
      
           #import "car.h"    int main(int argc, const char * argv[])    {        @autoreleasepool {                                Car *car = [[Car alloc] init];            car.carName = @"Defuli";            car.carType = @"SUB";            car.carNum = @"12";            NSLog(@"The Car name is %@ and the type is %@ and the No is %@.",car.carName,car.carType,car.carNum);                        [car setCarName:@"FUjian"];            [car setCarType:@"FLL"];                        NSLog(@"The Car name is %@ and the type is %@",car.carName,car.carType);        }        return 0;    }    mian中的实际用法