iOS - 代码Review (四)

#import <Foundation/Foundation.h>

@interface Person : NSObject

@property (nonatomic, copy, readonly) NSString *firstName;
@property (nonatomic, copy, readonly) NSString *lastName;

- (instancetype)initWithFirstName:(NSString *)firstName lastName:(NSString *)lastName;
@end


@implementation Person
- (instancetype)initWithFirstName:(NSString *)firstName lastName:(NSString *)lastName {
    if (self = [super init]) {
        _firstName = [firstName copy];
        _lastName = [lastName copy];
    }
    return self;
}

@end

 - (NSString *)description {
     return [NSString stringWithFormat:@"< %@ : %p, \" %@ %@\">", [self class], self, _firstName, _lastName ];
 }
 
 //person = <Person : 0x7f9996c38250, "levin eeo">

- (NSString *)debugDescription {
    return [NSString stringWithFormat:@"< %@ : %p, \" %@ %@\">", [self class], self, _firstName, _lastName ];
}

// po person 
// (Person *) $0 = 0x7f9996c38250 <Person : 0x7f9996c38250, "levin eoo">

#import <Foundation/Foundation.h>

@interface PointServer : NSObject
@property (nonatomic, copy) NSString *identifier;
@property (nonatomic, copy) NSString *title;
@property (nonatomic, assign) float xPoint;
@property (nonatomic, assign) float yPoint;

 - (instancetype)initWithIdentifier:(NSString *)identifier title:(NSString *)title x:(float)x y:(float)y;
对象中的值通过网络服务获取,在与网络服务通信过程中，通过identifer来代表景点,用服务器所提供的数据创建好某个点后
就不需要改动了.如果用其他语言来写比如golang会通过方法名大小写来控制外部访问权限,又例如Swift的private 和 public
所以为了把PointServer 做成不可变的类,需要把所有属性声明成readonly


@property (nonatomic, copy, readonly) NSString *identifier;
@property (nonatomic, copy, readonly) NNStrint *title;
@property (nonatomic, assign, readonly) float xPoint;
@property (nonatomic, assign, readonly) float yPoint;


如果强行改动这些值,编译器会报错.对象中的属性值可读但不可写。这就保证了PointServer类中的各个数据之间是相互
协调的。于是，开发者在使用对象肯定对底层数据reaonly的数据不会改动。因此，对象本身的数据结构不可能出现不一致的想象


@end