帮助创建与filteredArrayUsingPredicate一起使用的谓词
我正在尝试学习如何使用谓词，因此正在尝试将以下工作代码替换为filteredArrayUsingPredicate...
[filteredLocations removeAllObjects];
for (NSString *location in locations) {
NSRange range = [location rangeOfString:query options:NSCaseInsensitiveSearch];
if (range.length > 0) {
[filteredLocations addObject:location];
}
}
相反，我正在尝试...
[filteredLocations removeAllObjects];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF contains %@", searchText];
[filteredLocations addObjectsFromArray: [locations filteredArrayUsingPredicate:predicate]];
我没有得到与for循环rangeOfString相同的谓词结果。例如，对于字符串范围，searchText 返回一个包含 8 项的数组，而对于相同的值，使用谓词仅返回 2 项。另一个例子，hono 会在位置数组中找到 honolulu，但使用谓词不会找到任何内容。
据我了解，SELF 代表正在评估的对象对象，即。位置数组，所以我认为这是正确的语法。
任何帮助将不胜感激，
谢谢，约翰
I am trying to learn how to use predicates and so am trying to replace the following working code with filteredArrayUsingPredicate...
[filteredLocations removeAllObjects];
for (NSString *location in locations) {
NSRange range = [location rangeOfString:query options:NSCaseInsensitiveSearch];
if (range.length > 0) {
[filteredLocations addObject:location];
}
}
Instead I am trying....
[filteredLocations removeAllObjects];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF contains %@", searchText];
[filteredLocations addObjectsFromArray: [locations filteredArrayUsingPredicate:predicate]];
I am not getting the same results with the predicate as I am with for loop rangeOfString. With the range of string for example searchText returns an 8 item array while with the same value returns only 2 with the predicate. Another example, hono will find honolulu in the locations array while it will not find anything using the predicate.
As I understand it SELF represents the object object being evaluated ie. the locations array, so I think that is the correct syntax.
Any help would be appreciated
Thanks, John
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我认为在您的 for 循环中，您指定了一个选项 NSCaseInsensitiveSearch 但在谓词中您没有指定。
您可以尝试使用这个
更多详细信息可以在此处查看
NSPredicate 教程
I thought that in your for loop, you specify an option NSCaseInsensitiveSearch but in the predicate you didn't.
You can try with this one
More details can be looked at here
NSPredicate Tutorial