如果我的搜索谓词返回nil，则尝试弹出UIAlert
||
如果用户进行搜索并且谓词返回nil，我将尝试弹出一条警告“未找到记录”的警报。
我尝试了此操作，但从未收到警报。我只是得到一个空的tableview。
- (void)searchBarSearchButtonClicked:(UISearchBar *)searchBar {
if (self.sBar.text != nil){
NSPredicate *template = [NSPredicate predicateWithFormat:@\"name contains[cd] $SEARCH OR optionOne contains[cd] $SEARCH OR optionTwo contains[cd] $SEARCH\"];
NSDictionary *replace = [NSDictionary dictionaryWithObject:self.sBar.text forKey:@\"SEARCH\"];
NSPredicate *predicate = [template predicateWithSubstitutionVariables:replace];
[fetchedResultsController.fetchRequest setPredicate:predicate];
}
[[fetchedResultsController fetchedObjects] count];
if (fetchedResultsController.fetchedObjects != nil) {
//do nothing
} else {
//display alert
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:@\"No records match.\"
delegate:self cancelButtonTitle:@\"OK\" otherButtonTitles:nil];
[alert show];
[alert release];
}
NSError *error = nil;
if (![[self fetchedResultsController] performFetch:&error]) {
// Handle error
NSLog(@\"Unresolved error %@, %@\", error, [error userInfo]);
abort(); // Fail
}
[self.myTable reloadData];
[sBar resignFirstResponder];
}
没有找到相关结果
已邀请:
2 个回复
瞥同忙接
。谓词是一个表达式，其结果为或。而已。 您可以向索取其（返回一个数组），然后向该数组索取其，但是只有在调用之后才能执行此操作。茶鬼失形
- (void)searchBarSearchButtonClicked:(UISearchBar *)searchBar { if (self.sBar.text != nil) { NSPredicate *template = [NSPredicate predicateWithFormat:@\"name contains[cd] $SEARCH OR optionOne contains[cd] $SEARCH OR optionTwo contains[cd] $SEARCH\"]; NSDictionary *replace = [NSDictionary dictionaryWithObject:self.sBar.text forKey:@\"SEARCH\"]; NSPredicate *predicate = [template predicateWithSubstitutionVariables:replace]; [fetchedResultsController.fetchRequest setPredicate:predicate]; } NSError *error = nil; if (![[self fetchedResultsController] performFetch:&error]) { // Handle error NSLog(@\"Unresolved error %@, %@\", error, [error userInfo]); exit(-1); // Fail } if ([[fetchedResultsController fetchedObjects] count] != 0) { [self.myTable reloadData]; [sBar resignFirstResponder]; } else { //display alert UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:@\"No records match.\" delegate:self cancelButtonTitle:@\"OK\" otherButtonTitles:nil]; [alert show]; [alert release]; } }