[英]objc_getAssociatedObject returning null
我正在尝试使用objc_setAssociatedObject
传递对象
我正在尝试使用以下代码传递Evento
:
Evento *evento = (Evento*)[secAtt objectAtIndex:indexPath.row];
objc_setAssociatedObject(evento, @"evento", self, OBJC_ASSOCIATION_RETAIN);
后来我试图让这个evento
用下面的代码:
Evento *evento = objc_getAssociatedObject(self, "evento");
返回nil
编辑:更多代码:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];
[cell setSelectionStyle:UITableViewCellSelectionStyleNone];
NSString *sectionTitle = [sectionsTitles objectAtIndex:indexPath.section];
NSArray *secAtt = [attractions objectForKey:sectionTitle];
Evento *evento = (Evento*)[secAtt objectAtIndex:indexPath.row];
objc_setAssociatedObject(self, @"evento", evento, OBJC_ASSOCIATION_RETAIN);
NSString *tipoEntretenimento = evento.entretenimento.tipo.descricao;
NSLog(@"tipo %@", tipoEntretenimento);
UIImageView *imgCategoria = (UIImageView *)[cell.contentView viewWithTag:30];
//[imgCategoria setContentMode:UIViewContentModeScaleAspectFit];
if([tipoEntretenimento isEqualToString:@"Bares"])
[imgCategoria setImage:[UIImage imageNamed:@"bares.png"]];
else if ([tipoEntretenimento isEqualToString:@"Crianca"])
[imgCategoria setImage:[UIImage imageNamed:@"crianca.png"]];
else if ([tipoEntretenimento isEqualToString:@"Guloseimas"])
[imgCategoria setImage:[UIImage imageNamed:@"guloseimas.png"]];
else if ([tipoEntretenimento isEqualToString:@"Restaurantes"])
[imgCategoria setImage:[UIImage imageNamed:@"restaurantes.png"]];
else if ([tipoEntretenimento isEqualToString:@"Teatro"])
[imgCategoria setImage:[UIImage imageNamed:@"teatro.png"]];
else if ([tipoEntretenimento isEqualToString:@"Shows"])
[imgCategoria setImage:[UIImage imageNamed:@"shows"]];
else if ([tipoEntretenimento isEqualToString:@"Dança"])
[imgCategoria setImage:[UIImage imageNamed:@"danca.png"]];
else if ([tipoEntretenimento isEqualToString:@"Concertos"])
[imgCategoria setImage:[UIImage imageNamed:@"concerto.png"]];
else if ([tipoEntretenimento isEqualToString:@"Cinema"])
[imgCategoria setImage:[UIImage imageNamed:@"cinema.png"]];
UIFont *roboto = [UIFont fontWithName:@"Roboto-Bold" size:16];
UILabel *lblNomeEvento = (UILabel *)[cell.contentView viewWithTag:10];
lblNomeEvento.text = evento.entretenimento.nome;
lblNomeEvento.font = roboto;
Agenda *agenda = nil;
if([evento.listaAgendas count] > 0)
agenda = (Agenda *)[evento.listaAgendas objectAtIndex:0];
NSLog(@"agenda %@", agenda.description);
UIImageView *imgevento = (UIImageView *)[cell.contentView viewWithTag:20];
[imgevento setContentMode:UIViewContentModeScaleAspectFit];
[imgevento setImage:[UIImage imageNamed:@"pin.png"]];
UIButton *btnCompartilhar = (UIButton *)[cell.contentView viewWithTag:40];
[btnCompartilhar.titleLabel setHidden:YES];
btnCompartilhar.titleLabel.text = evento.entretenimento.nome;
[btnCompartilhar addTarget:self action:@selector(compartilharClick:) forControlEvents:UIControlEventTouchDown];
UIButton *btnFavoritar = (UIButton *)[cell.contentView viewWithTag:50];
[btnFavoritar addTarget:self action:@selector(favoritarClick:) forControlEvents:UIControlEventTouchDown];
return cell;
}
后来当我尝试获取对象时:
-(void) compartilharClick:(id)sender {
Evento *evento = (Evento *)objc_getAssociatedObject(self, "evento");
UIActionSheet *popup = [[UIActionSheet alloc] initWithTitle:@"Compartilhar:" delegate:self cancelButtonTitle:@"Cancelar" destructiveButtonTitle:nil otherButtonTitles:
@"Facebook",
@"Google+",
@"Twitter",
@"Outros",
nil];
popup.tag = 1;
[popup showInView:[UIApplication sharedApplication].keyWindow];
}
objc_setAssociatedObject
的第一个参数应为self
(第三个参数应为evento
)
建立关联时,您会感到self
evento
甚至evento
,请尝试:
objc_setAssociatedObject(self, @"evento", evento, OBJC_ASSOCIATION_RETAIN);
编辑: objc_setAssociatedObject
的键(您正在使用“ evento”),需要是唯一的指针。 如果您检查参考链接,他们建议使用选择器作为键,因为它保证是唯一的。
一次定义密钥( char *const AssoicateKey = "evento";
),它将开始起作用。
另外,除非表中只有1行,否则代码将无法工作。 每次使用单元格时,您都将覆盖关联。 检索它时,它将使最后一个单元格的对象出队。 您可以将对象与按钮相关联,并将其从发送者处移出,以使其生效。
这里的问题可能是因为当函数需要const void *key
时,您使用NSString作为const void *key
OBJC_EXPORT void objc_setAssociatedObject(id object, const void *key, id value, objc_AssociationPolicy policy)
尝试添加static char *EventToKey = "EventToKey";
高于您的实现。
然后将objc_getAssociatedObject
和objc_setAssociatedObject
使用更改为
objc_setAssociatedObject(self, EventToKey, evento, OBJC_ASSOCIATION_RETAIN);
objc_getAssociatedObject(self, EventToKey);
您使用的密钥在两个调用中必须是相同的指针。 不是一个具有相同值的字符串(如果您两次传递“ evento”,则指针可能会不同),并且与您所做的一样,最确定的是一个NSString * @“ evento”和一个C字符串“ evento”。
最简单的方法是创建一个静态变量并传递地址。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.