Question

I want that when the user puts a number in a textfield this number will be used for lots of operations, but this number can’t be 0, i created a error message that will be displayed if user clicks on the “next” button whit a 0 on the textfield, but this message don’t have time to appear, because this button takes the user to another view, how do i tell the button to stay in that view until the number is ok? my button implementation:

- (IBAction)calc:(id)sender {  

    int mynumber;
    mynumber = [textfieldnumber.text intValue];

    if (mynumber==0) {

        NSString *errorstr = [[NSString alloc] initWithFormat:@"Please, set the number of people..."];
        labelerror.text = errorstr;


    }


}

Answer 1

Remove the Segue from Storyboards. Then make a new one that goes from file owner, or the little yellow box at the bottom of a selected view to the new modalViewController. Set it’s identifier and remember it. Then change this:

- (IBAction)calc:(id)sender {  

int mynumber;
mynumber = [textfieldnumber.text intValue];

if (mynumber==0) {

    NSString *errorstr = [[NSString alloc] initWithFormat:@"Please, set the number of people..."];
    labelerror.text = errorstr;


}


}

to this:

- (IBAction)calc:(id)sender {  

int mynumber;
mynumber = [textfieldnumber.text intValue];

if (mynumber==0) {

    NSString *errorstr = [[NSString alloc] initWithFormat:@"Please, set the number of people..."];
    labelerror.text = errorstr;


}else{
    [self performSegueWithIdentifier:identifies sender:self];

}

}

or

- (IBAction)calc:(id)sender {  

int mynumber;
mynumber = [textfieldnumber.text intValue];

if (mynumber==0) {

    NSString *errorstr = [[NSString alloc] initWithFormat:@"Please, set the number of people..."];
    labelerror.text = errorstr;


}else{
    [self presentModalViewController:viewController animated:YES];
}


}