我有一个带有NSMutableArray属性的单例类,我想要添加对象并删除对象。出于某种原因,我得到了:
-[__NSDictionaryI setObject:forKey:]: unrecognized selector sent to instance 0x1edf24c0
尝试添加时出现异常。以下是单例接口的相关代码:
//outbox item is the type of objects to be held in the dictionary
@interface OutboxItem : NSObject
@property (nonatomic, assign) unsigned long long size;
@end
@interface GlobalData : NSObject
@property (nonatomic, copy) NSMutableDictionary *p_outbox;
+ (GlobalData*)sharedGlobalData;
@end
单身人士的实施:
@implementation GlobalData
@synthesize p_outbox;
static GlobalData *sharedGlobalData = nil;
+ (GlobalData*)sharedGlobalData {
if (sharedGlobalData == nil) {
sharedGlobalData = [[super allocWithZone:NULL] init];
sharedGlobalData.p_outbox = [[NSMutableDictionary alloc] init];
}
return sharedGlobalData;
}
+ (id)allocWithZone:(NSZone *)zone {
@synchronized(self)
{
if (sharedGlobalData == nil)
{
sharedGlobalData = [super allocWithZone:zone];
return sharedGlobalData;
}
}
return nil;
}
- (id)copyWithZone:(NSZone *)zone {
return self;
}
@end
这是抛出异常的代码:
GlobalData* glblData=[GlobalData sharedGlobalData] ;
OutboxItem* oItem = [OutboxItem alloc];
oItem.size = ...;//some number here
[glblData.p_outbox setObject:oItem forKey:...];//some NSString for a key
我错过了一些非常明显的事情吗?
答案 0 :(得分:3)
问题在于你的财产:
@property (nonatomic, copy) NSMutableDictionary *p_outbox;
属性的copy
语义导致在为属性赋值时生成的字典副本。但是,即使在copy
上调用,字典的NSDictionary
方法也始终返回不可变NSMutableDictionary
。
要解决此问题,您必须为属性创建自己的setter方法:
// I'm a little unclear what the actual name of the method will be.
// It's unusual to use underscores in property names. CamelCase is the standard.
- (void)setP_outbox:(NSMutableDictionary *)dictionary {
p_outbox = [dictionary mutableCopy];
}
答案 1 :(得分:2)
你的
@property (nonatomic, copy) NSMutableDictionary *p_outbox;
正在创建您分配给它的该对象的副本。
当您为其分配NSMutableDictionary
时,它会创建NSMutableDictionary
对象的副本,NSDictionary
不是可变副本。
所以将其改为
非ARC
@property (nonatomic, retain) NSMutableDictionary *p_outbox;
对于ARC
@property (nonatomic, strong) NSMutableDictionary *p_outbox;