Question

我有以下代码：

   NSMutableSet* localSet = [[NSMutableSet alloc] initWithArray:symbols];
NSMutableArray* fetchedSymbolsArray = [NSMutableArray array];

for (NSDictionary* symbol in fetchedSymbols) {
    [fetchedSymbolsArray addObject:[NSDictionary dictionaryWithObject:[symbol valueForKey:@"symbol"] forKey:@"symbol"]];
}

NSMutableSet* serverSet = [[NSMutableSet alloc] initWithArray:fetchedSymbolsArray];

[localSet unionSet:serverSet];

for (NSDictionary* symbol in localSet) {
    NSLog(@"%@",[symbol valueForKey:@"symbol"]);
}

我希望serverSet中的所有内容都在localSet中。此代码不反映这一点。

如果没有将任何重复项添加到localSet中，也会更好。

编辑：这是我的日志：

2011-08-16 17:46:28.887 Stream[94612:207] YHOO
2011-08-16 17:46:28.887 Stream[94612:207] GOOG
2011-08-16 17:46:28.887 Stream[94612:207] INTC
2011-08-16 17:46:28.888 Stream[94612:207] BIDU
2011-08-16 17:46:28.888 Stream[94612:207] INTC
2011-08-16 17:46:28.888 Stream[94612:207] BIDU
2011-08-16 17:46:28.888 Stream[94612:207] AAPL
2011-08-16 17:46:28.888 Stream[94612:207] AAPL
2011-08-16 17:46:28.889 Stream[94612:207] AMD
2011-08-16 17:46:28.889 Stream[94612:207] GMCR

Answer 1

尝试[localSet unionSet:serverSet]

修改

这里的代码只使用符号代替NSDictionary s：

NSArray *symbols = [NSArray arrayWithObjects:@"AAPL",@"GOOG",@"INTC",@"YHOO",nil]; NSArray *fetchedSymbols = [NSArray arrayWithObjects:@"AMD",@"BIDU",@"GOOG",@"GMCR",@"INTC",@"YHOO",nil]; NSMutableSet* localSet = [[NSMutableSet alloc] initWithArray:symbols]; NSMutableSet* serverSet = [[NSMutableSet alloc] initWithArray:fetchedSymbols]; [localSet unionSet:serverSet]; for (id symbol in localSet) { NSLog(@"%@",symbol); } 2011-08-16 18:25:22.107 so7086790[39810:a0f] YHOO 2011-08-16 18:25:22.116 so7086790[39810:a0f] AMD 2011-08-16 18:25:22.116 so7086790[39810:a0f] AAPL 2011-08-16 18:25:22.116 so7086790[39810:a0f] INTC 2011-08-16 18:25:22.117 so7086790[39810:a0f] GMCR 2011-08-16 18:25:22.117 so7086790[39810:a0f] GOOG 2011-08-16 18:25:22.118 so7086790[39810:a0f] BIDU

Answer 2

你在union中错误地使用了serverSet和localSet - 被修改的集合是方法“unionSet：”的接收者，而不是参数。

NSMutableSet* localSet = [[NSMutableSet alloc] initWithArray:symbols];
NSMutableArray* fetchedSymbolsArray = [NSMutableArray array];

for (NSDictionary* symbol in fetchedSymbols) {
    [fetchedSymbolsArray addObject:[NSDictionary dictionaryWithObject:[symbol valueForKey:@"symbol"] forKey:@"symbol"]];
}

NSMutableSet* serverSet = [[NSMutableSet alloc] initWithArray:fetchedSymbolsArray];

[localSet unionSet:serverSet];

for (NSDictionary* symbol in localSet) {
    NSLog(@"%@",[symbol valueForKey:@"symbol"]);
}

请注意，根据定义，set不允许重复输入。但这并不意味着你不会在字典中有重复的值，这意味着你不会有两次相同的“相等”字典（如果它们各自拥有相同数量的条目，则两个字典是相同的，对于给定的键，每个字典中的相应值对象满足isEqual：test）。

为避免重复特定字典值，您必须自己添加它们。我建议你创建一个临时集，其中包含“symbol”键的实际值，并使用该集来测试它是否已被添加。

NSMutableSet *localSetValues = [[NSMutableSet alloc] init];

// Add local set values
for (NSDictionary *symbol in localSet) {
    [localSetValues addObject:[symbol valueForKey:@"symbol"]];
}
// Add server set, conditionally
for (NSDictionary *symbol in serverSet) {
    if (![localSetValues containsObject:[symbol valueForKey:@"symbol"]]) {
        [localSet addObject:symbol];
    }
}

// Cleanup
[localSetValues release];

而不是

[localSet unionSet:serverSet];

结合NSMutableSets的问题

2 个答案: