声明：
-(id)initWithName:(NSString *)name andAge:(int)age andSex:(NSString *)sex andTalent:(NSString *)talent andMate:(id)mate;
+(id)machineWithName:(NSString *)name andAge:(int)age andSex:(NSString *)sex andTalent:(NSString *)talent andMate:(id)mate;

实现：
-(id)initWithName:(NSString *)name andAge:(int)age andSex:(NSString *)sex andTalent:(NSString *)talent andMate:(id)mate
{
    self=[super init];
    if (self)
    {
        _name=name;
        _age=age;
        _sex=sex;
        _talent=talent;
        _mate=mate;
    }
    return self;
}

+(id)machineWithName:(NSString *)name andAge:(int)age andSex:(NSString *)sex andTalent:(NSString *)talent andMate:(id)mate
{
    Machine *mac=[[Machine alloc]initWithName:name andAge:age andSex:sex andTalent:talent andMate:mate];
    return [mac autorelease];//便利构造器内部已经实现内存管理
}

调用：
Machine *mac=[Machine machineWithName:@"machine" andAge:5 andSex:@"?" andTalent:@"HP 10,MP 0,PW 100" andMate:nil];

注意：
便利构造器方法以类名开头
类方法内部不能用实例变量
类方法只能以类（名）来调用

声明：
-(id)initWithName:(NSString *)name andAge:(int)age andSex:(NSString *)sex andTalent:(NSString *)talent andMate:(id)mate;
+(id)machineWithName:(NSString *)name andAge:(int)age andSex:(NSString *)sex andTalent:(NSString *)talent andMate:(id)mate;

实现：
-(id)initWithName:(NSString *)name andAge:(int)age andSex:(NSString *)sex andTalent:(NSString *)talent andMate:(id)mate
{
    self=[super init];
    if (self)
    {
        _name=name;
        _age=age;
        _sex=sex;
        _talent=talent;
        _mate=mate;
    }
    return self;
}

+(id)machineWithName:(NSString *)name andAge:(int)age andSex:(NSString *)sex andTalent:(NSString *)talent andMate:(id)mate
{
    Machine *mac=[[Machine alloc]initWithName:name andAge:age andSex:sex andTalent:talent andMate:mate];
    return [mac autorelease];//便利构造器内部已经实现内存管理
}

调用：
Machine *mac=[Machine machineWithName:@"machine" andAge:5 andSex:@"?" andTalent:@"HP 10,MP 0,PW 100" andMate:nil];

注意：
便利构造器方法以类名开头
类方法内部不能用实例变量
类方法只能以类（名）来调用