ios - 获取与 NSDictionary 对象类型相关的错误

Question

我想根据国家名称或国家 ISD 代码过滤国家列表。例如，如果用户键入“9”，则应将印度添加到过滤数组中，因为印度的 ISD 代码为“+91”。我的数据源包含国家名称、ISD 代码等所有信息。

这是我的数组的结构:

- (void)viewDidLoad
{
    [super viewDidLoad];

    arrTotalCountries    = [[NSMutableArray alloc] init];
    arrFilteredCountries = [[NSArray alloc] init];

    NSDictionary *dic1 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@"1",@"India",@"IN",@"+91",nil] forKeys:[NSArray arrayWithObjects:@"CountryId",@"CountryName",@"CountryCode",@"ISDCode",nil]];
    NSDictionary *dic2 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@"2",@"Australia",@"AU",@"+42",nil] forKeys:[NSArray arrayWithObjects:@"CountryId",@"CountryName",@"CountryCode",@"ISDCode",nil]];
    NSDictionary *dic3 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@"3",@"New Zealand",@"NZ",@"+63",nil] forKeys:[NSArray arrayWithObjects:@"CountryId",@"CountryName",@"CountryCode",@"ISDCode",nil]];
    NSDictionary *dic4 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@"4",@"South Africa",@"SA",@"+94",nil] forKeys:[NSArray arrayWithObjects:@"CountryId",@"CountryName",@"CountryCode",@"ISDCode",nil]];
    NSDictionary *dic5 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@"5",@"England",@"EN",@"+75",nil] forKeys:[NSArray arrayWithObjects:@"CountryId",@"CountryName",@"CountryCode",@"ISDCode",nil]];
    NSDictionary *dic6 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@"6",@"Israel",@"IS",@"+86",nil] forKeys:[NSArray arrayWithObjects:@"CountryId",@"CountryName",@"CountryCode",@"ISDCode",nil]];
    NSDictionary *dic7 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@"7",@"Afghanistan",@"AF",@"+27",nil] forKeys:[NSArray arrayWithObjects:@"CountryId",@"CountryName",@"CountryCode",@"ISDCode",nil]];
    NSDictionary *dic8 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@"8",@"Ireland",@"IR",@"+18",nil] forKeys:[NSArray arrayWithObjects:@"CountryId",@"CountryName",@"CountryCode",@"ISDCode",nil]];

    [arrTotalCountries addObject:dic1];
    [arrTotalCountries addObject:dic2];
    [arrTotalCountries addObject:dic3];
    [arrTotalCountries addObject:dic4];
    [arrTotalCountries addObject:dic5];
    [arrTotalCountries addObject:dic6];
    [arrTotalCountries addObject:dic7];
    [arrTotalCountries addObject:dic8];

    [self filterContentForSearchText:@"9"];
} 

这就是我尝试过滤数组的方式。出于测试目的，我刚刚通过了静态“9”。

- (void)filterContentForSearchText:(NSString *)searchText
{
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(SELF.CountryName BEGINSWITH[cd] %@) OR (SELF.ISDCode BEGINSWITH[cd] %@)", searchText];
    NSArray *filtered = [arrTotalCountries filteredArrayUsingPredicate:predicate];
    NSLog(@"%@",[filtered description]);
}

我在运行时遇到以下错误。

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Can't do a substring operation with something that isn't a string (lhs = +91 rhs = ViewController)'

我认为这是因为，在字典中，键“ISDCode”有类似“+91”的值。我该如何解决这个问题？

Answer 1

你的谓词需要两个参数，但你只传递了1个，它应该是

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(SELF.CountryName BEGINSWITH[cd] %@) OR (SELF.ISDCode BEGINSWITH[cd] %@)", searchText, searchText];

通过仅提供 1 个参数，第二个随机内存被占用，在本例中结果是一个 View Controller 。