How to call an API runtime when I start typing in UITextfield?

Here is the one example:

Image 1 - It contain a UITextfield say emailTextField. When I start typing then according to its keyword in background one API will call which will gives response according to your keyword.

API used for searching is like

url/collaborator/search

and parameters are,

1. token 
2. term

Image 2 - When I started typing like "ma", then in background that API call has to call, i.e API call be like

url/collaborator/search?token=kdkhu67tdndodAK803i939ndAJDEw & term=ma

so it will give response, and that response it has to be show like drop down which is shown in image

Image 3 - If type specific name, then according to its data it has to filter the emails and specific email has to come, and when I click on it it has to add in textfield. I want single search as well as multiple email search.

url/collaborator/search?token=kdkhu67tdndodAK803i939ndAJDEw & term=komal

Currently I want to implement single at a time, if more than one can able do or add then no issue.

So, how to call API at run time when I start typing in textfield and get data in array?

Write below code,

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    NSLog(@"Data is : %@",_ccTextField.text);


    [self collaboratorApiMethod:_ccTextField.text];

    return YES;
}


// This metod is used to add collaborator, it will call API according to enetered data, JSON will receive
-(void)collaboratorApiMethod:(NSString*)valueFromTextField
{
   NSString *url =[NSString stringWithFormat:@"%@/collaborator/search?token=%@&term=%@",[userDefaults objectForKey:@"token"],valueFromTextField];
   // so this will generate in url

   // call api (REST API call)
   // you will get JSON data, store in array/dictionaries
}

Assume that, you got an array which contains a list of emails. Now that email you have to show suggestions when a user starts typing in textField and according to its value data will filter and show suggestion.

write below code,

- (UITableViewCell *)autoSuggestionField:(UITextField *)field tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath forText:(NSString *)text {

  userSearchDataCell *cell=[tableView dequeueReusableCellWithIdentifier:@"userSearchDataCellId"];

    if (cell == nil)
    {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"userSearchDataCell" owner:self options:nil];
        cell = [nib objectAtIndex:0];
    }

    NSArray *emails = emailArray;

   if (text.length > 0) {
        NSPredicate *filterPredictate = [NSPredicate predicateWithFormat:@"SELF CONTAINS[cd] %@",text];
        months = [emailArray filteredArrayUsingPredicate:filterPredictate];
   }


    cell.emailLabel.text = emails[indexPath.row];
}


 - (NSInteger)autoSuggestionField:(UITextField *)field tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section forText:(NSString *)text {

    if (text.length == 0) {
        return emailArray.count;
    }

    NSPredicate *filterPredictate = [NSPredicate predicateWithFormat:@"SELF CONTAINS[cd] %@", text];
     NSInteger count = [emailArray filteredArrayUsingPredicate:filterPredictate].count;
    return count;

}


- (CGFloat)autoSuggestionField:(UITextField *)field tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath forText:(NSString *)text {
    return 65;
}


- (void)autoSuggestionField:(UITextField *)field tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath forText:(NSString *)text {
    // NSLog(@"Selected suggestion at index row - %ld", (long)indexPath.row);

    NSArray *emails = emailArray;

    if (text.length > 0) {
        NSPredicate *filterPredictate = [NSPredicate predicateWithFormat:@"SELF CONTAINS[cd] %@", text];
        months = [emailArray filteredArrayUsingPredicate:filterPredictate];
    }

   self.emailLabel.text =  emails[indexPath.row];

}