我已经阅读了NSCopying
文档,但我仍然不确定如何实现所需的内容。
我的类Vendor
@interface Vendor : NSObject
{
NSString *vendorID;
NSMutableArray *availableCars;
BOOL atAirport;
}
@property (nonatomic, copy) NSString *vendorID;
@property (nonatomic, retain) NSMutableArray *availableCars;
@property (nonatomic, assign) BOOL atAirport;
- (id)initFromVehVendorAvailsDictionary:(NSDictionary *)vehVendorAvails;
@end
Vendor
类有一个名为Car
的对象数组。
我的Car
对象:
@interface Car : NSObject
{
BOOL isAvailable;
NSString *transmissionType;
NSMutableArray *vehicleCharges;
NSMutableArray *fees;
}
@property (nonatomic, assign) BOOL isAvailable;
@property (nonatomic, copy) NSString *transmissionType;
@property (nonatomic, retain) NSMutableArray *vehicleCharges;
@property (nonatomic, retain) NSMutableArray *fees;
- (id) initFromVehicleDictionary:(NSDictionary *)vehicleDictionary;
@end
因此,Vendor
包含一个Car
对象数组。Car
包含2个其他自定义对象的数组。
Vendor
和Car
都是从字典中初始化的。我将添加其中一个方法,它们可能是相关的,也可能是无关的。
-(id)initFromVehVendorAvailsDictionary:(NSDictionary *)vehVendorAvails {
self.vendorCode = [[vehVendorAvails objectForKey:@"Vendor"]
objectForKey:@"@Code"];
self.vendorName = [[vehVendorAvails objectForKey:@"Vendor"]
objectForKey:@"@CompanyShortName"];
self.vendorDivision = [[vehVendorAvails objectForKey:@"Vendor"]
objectForKey:@"@Division"];
self.locationCode = [[[vehVendorAvails objectForKey:@"Info"]
objectForKey:@"LocationDetails"]
objectForKey:@"@Code"];
self.atAirport = [[[[vehVendorAvails objectForKey:@"Info"]
objectForKey:@"LocationDetails"]
objectForKey:@"@AtAirport"] boolValue];
self.venLocationName = [[[vehVendorAvails objectForKey:@"Info"]
objectForKey:@"LocationDetails"]
objectForKey:@"@Name"];
self.venAddress = [[[[vehVendorAvails objectForKey:@"Info"]
objectForKey:@"LocationDetails"]
objectForKey:@"Address"]
objectForKey:@"AddressLine"];
self.venCountryCode = [[[[[vehVendorAvails objectForKey:@"Info"]
objectForKey:@"LocationDetails"]
objectForKey:@"Address"]
objectForKey:@"CountryName"]
objectForKey:@"@Code"];
self.venPhone = [[[[vehVendorAvails objectForKey:@"Info"]
objectForKey:@"LocationDetails"]
objectForKey:@"Telephone"]
objectForKey:@"@PhoneNumber"];
availableCars = [[NSMutableArray alloc] init];
NSMutableArray *cars = (NSMutableArray *)[vehVendorAvails objectForKey:@"VehAvails"];
for (int i = 0; i < [cars count]; i++) {
Car *car = [[Car alloc] initFromVehicleDictionary:[cars objectAtIndex:i]];
[availableCars addObject:car];
[car release];
}
self.venLogo = [[[vehVendorAvails objectForKey:@"Info"]
objectForKey:@"TPA_Extensions"]
objectForKey:@"VendorPictureURL"];
return self;
}
所以总结一下这个可怕的问题。
我需要复制一个Vendor
对象数组。我认为我需要在Vendor
上实现NSCopying
协议,这可能意味着我也需要在Car
上实现它,因为Vendor
拥有一个Car
数组,这意味着我还需要在属于Car
对象的两个数组中的类上实现它。
如果我能得到一些关于在Vendor
上实现NSCopying
协议的指导,我将不胜感激,我在任何地方都找不到任何关于这方面的教程。
发布于 2010-11-04 00:42:42
要实现NSCopying,您的对象必须响应-copyWithZone:
选择器。下面是你如何声明你符合它:
@interface MyObject : NSObject <NSCopying> {
然后,在对象的实现( .m
文件)中:
- (id)copyWithZone:(NSZone *)zone
{
// Copying code here.
}
你的代码应该做什么?首先,创建一个新的对象实例--你可以调用[[[self class] alloc] init]
来获得当前类的一个初始化的object,这对于子类化很有效。然后,对于作为支持复制的NSObject
子类的任何实例变量,您可以为新对象调用[thatObject copyWithZone:zone]
。对于原始类型(int
、char
、BOOL
和friends),只需将变量设置为相等即可。因此,对于您的obejct,它将如下所示:
- (id)copyWithZone:(NSZone *)zone
{
id copy = [[[self class] alloc] init];
if (copy) {
// Copy NSObject subclasses
[copy setVendorID:[[self.vendorID copyWithZone:zone] autorelease]];
[copy setAvailableCars:[[self.availableCars copyWithZone:zone] autorelease]];
// Set primitives
[copy setAtAirport:self.atAirport];
}
return copy;
}
发布于 2017-01-04 01:19:35
此答案类似于已接受的答案,但使用allocWithZone:
并针对ARC进行更新。NSZone是分配内存的基础类。虽然忽略NSZone
在大多数情况下可能有效,但它仍然是不正确的。
要正确实现NSCopying
,您必须实现一个协议方法,该方法分配对象的新副本,其属性与原始值匹配。
在标头的接口声明中,指定您的类实现NSCopying
协议:
@interface Car : NSObject<NSCopying>
{
...
}
在.m实现中,添加如下所示的-(id)copyWithZone
方法:
- (id)copyWithZone:(NSZone*)zone
{
Car* carCopy = [[[self class] allocWithZone:zone] init];
if (carCopy)
{
carCopy.isAvailable = _isAvailable;
carCopy.transmissionType = _transmissionType;
... // assign all other properties.
}
return carCopy;
}
https://stackoverflow.com/questions/4089238
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