2013-02-06 113 views
2

这段代码会导致错误,但它应该是正确的。将NSNumber对象添加到NSMutableArray

(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    NSNumber *rowNumber = [[NSNumber alloc] initWithInt:indexPath.row]; 
    [genreArray addObject:rowNumber]; 
    [self.tableView reloadData]; 
} 

genreArrayNSMutableArray

但对一个cell触摸我得到这个错误

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '-[__NSCFArray insertObject:atIndex:]: mutating method sent to immutable object' 
*** First throw call stack: 
(0x1c9c012 0x10d9e7e 0x1c9bdeb 0x1d1c9a5 0x1d1c8b0 0x7b4c 0xcd285 0xcd4ed 0xad75b3 0x1c5b376 0x1c5ae06 0x1c42a82 0x1c41f44 0x1c41e1b 0x1bf67e3 0x1bf6668 0x1dffc 0x271d 0x2645) 
libc++abi.dylib: terminate called throwing an exception 

有没有人有一个想法,为什么这是不工作?

+0

做除了答案简单,你可以改变' NSNumber * rowNumber = [[NSNumber alloc] initWithInt:indexPath.row];'带'NSNumber * rowNumber = @(indexPath.row);' – graver

+1

你分配了genreArray = [[NSMutableArray alloc] init];' – laxonline

+0

问题是我把它分配为NSMutableArray,但后来我写道:genreArray = someOtherArray; someOtherArray是一个数组,而不是一个可变数组。现在我分配它[NSMutableArray arrayWithArray:someOtherArray];这样可行! – Wed

回答

3

因为你的阵列是不可变的... 检查要实例化genreArray代码:既有类型声明,和实例化必须以NSMutableArray

//valid declaration + instantiation 
NSMutableArray *genreArray = [NSArray array]; 

//valid at compile-time : genreArray is supposed to be mutable 
//however will result in runtime error : genreArray is actually immutable 
[genreArray addObject:anObject]; 
+0

我发现了这个问题。有一个worng初始化,谢谢=) – Wed