NSNumber

    int age = 10 ;
    double height = 1.78;
    float  weight = 70.33;
    //将基本数据类型转换成对象类型
    NSNumber *ageN = [NSNumber numberWithInt:age];
    NSNumber *heightN = [NSNumber numberWithDouble:height];
    NSNumber *weightN = [NSNumber numberWithFloat:weight];
    //将对象类型转换成基本数据类型
    int agen = [ageN intValue];
    double heightn = [heightN doubleValue];
    float weightn = [weightN floatValue];
    //基本数据类型转换成对象类型简写(开发一般这么写)
    //如果传入的是变量那么必须要在@后面写上(),如果传入常量，那么@后面的()可以省略
    NSNumber *number = @(age);
    NSNumber *number2 = @23333.3333;