Question

NSMutableDictionary *dic0 = [[NSMutableDictionary alloc] initWithObjectsAndKeys:@"string0", @"key0", nil];
NSDictionary *dic1 = [[NSDictionary alloc] initWithObjectsAndKeys:@"string1", @"key1", nil];
NSDictionary *dic2 = [[NSDictionary alloc] initWithObjectsAndKeys:@"string2", @"key2", nil];
NSDictionary *dic3 = [[NSDictionary alloc] initWithObjectsAndKeys:@"dic3", @"key3", nil];

NSArray *arrayOri = [[NSArray alloc] initWithObjects:dic0, dic1, dic2, nil];

//here means a deep copy
NSMutableArray *arrayDeepCopy = [[NSMutableArray alloc] initWithArray:arrayOri copyItems:YES];

NSRange range = {0, 2};
NSArray *subArray = [arrayOri subarrayWithRange:range];
[arrayDeepCopy addObject:dic3];

NSLog(@"arrayOri not merge %@", arrayOri);

//merge one object
[dic0 setObject:@"mutableV" forKey:@"mutableKey"];
//dealloc one object
[dic1 dealloc];

NSLog(@"arrayOri %@  ", arrayOri);
NSLog(@"subArray %@  ", subArray);

崩溃在这里，因为dic1 dealloced，如果深拷贝，为什么原始对象对新对象有效？

NSLog(@"array %@  ", arrayDeepCopy);

what initWithArray:(NSArray *)array copyItems:(BOOL)flag  do after all??

Answer 1

问题是dic1是一个不可变对象。因此将它复制到内存中是没有意义的，因此arrayDeepCopy保存指向原始dic1对象的指针。当你解除分配它时，它会从存储它的所有数组中消失如果您想拥有真正的深层副本，则必须实例化NSMutableDictionary。

initWithArray：（NSArray *）array copyItems：（BOOL）标志

1 个答案: