如何编解码NSCalendarUnit

Question

如何像其他对象一样编码和解码NSCalendarUnit，如

self.myStr = [decoder decodeObjectForKey:@"myStr"];
[encoder encodeObject:self.myStr forKey:@"myStr"];

试图将NSCalendarUnit保存在NSNumber中，像这样的@(self.repetition);，但是当我登录时会得到64。

我想对NSCalendarUnit进行编码并保存，稍后必要时对其进行解码，并使用它进行比较，如下面的if(xxxxx == NSCalendarUnit)所示

Answer 1

NSCalendarUnit是一个无符号长，因此可以使用NSNumber上的两个方法对未签名的long进行“装箱”(使其成为一个对象)：

NSCalendarUnit someNSCalendarUnit = NSCalendarUnitDay;
NSNumber *boxed = [NSNumber numberWithUnsignedLong:someNSCalendarUnit];

和

NSCalendarUnit unboxed = [boxed unsignedLongLongValue];
// now, unboxed == someNSCalendarUnit

您可能知道如何编码解码NSNumbers，只需在编码/解码方法中添加附加的方框步骤.

- (void)encodeWithCoder:(NSCoder*)encoder {
    [super encodeWithCoder:encoder];

    NSNumber *boxed = [NSNumber numberWithUnsignedLong:self.someNSCalendarUnit];
    [encoder encodeObject:boxed forKey:@"someNSCalendarUnit"];
    // ...

}

- (id)initWithCoder:(NSCoder*)aDecoder {
    self = [super initWithCoder:aDecoder];
    if (self) {
        NSNumber *boxed = [aDecoder decodeObjectForKey:@"someNSCalendarUnit"];
        _someNSCalendarUnit = [boxed unsignedLongLongValue];
        // ...
    }
    return self;
}

Answer 2

NSCalendarUnit是一个选项集(NS_OPTIONS)，这意味着NSCalendarUnit值可以是单元的任何值、一个值或多个值。您需要执行一个位掩码 if ((xxxx & NSCalendarUnitHour) != 0)来检查值。

您可以像现在一样将值编码为NSNumber，并在解码时使用NSNumber.unsignedInteger获取值(请注意，NSCalendarUnit的枚举被定义为NSUInteger)。(注意，还可以使用NSInteger将值存储为-[NSCoder encodeInteger:forKey:]。)

Serialisation

[encoder encodeObject:@(self.repetition) forKey:@"repetition"];

Deserialisation

self.repetition = [[decoder decodeObjectOfClass:[NSNumber class] 
                   forKey:@"repetition"] unsignedInteger];

检查

if ((self.repetition & NSCalendarUnitHour) != 0) {
    // Do something
} else if ((self.repetition & NSCalendarUnitMinute) != 0) {
    // Do something
}