Displaying a message in iOS which has the same functionality as Toast in Android

You can make use of MBProgressHUD project.

Use HUD mode MBProgressHUDModeText for toast-like behaviour,

MBProgressHUD *hud = [MBProgressHUD showHUDAddedTo:self.navigationController.view animated:YES];

// Configure for text only and offset down
hud.mode = MBProgressHUDModeText;
hud.label.text = @"Some message...";
hud.margin = 10.f;
hud.yOffset = 150.f;
hud.removeFromSuperViewOnHide = YES;

[hud hideAnimated:YES afterDelay:3];

NSString *message = @"Some message...";

UIAlertView *toast = [[UIAlertView alloc] initWithTitle:nil
                                                message:message
                                               delegate:nil
                                      cancelButtonTitle:nil
                                      otherButtonTitles:nil, nil];
[toast show];
        
int duration = 1; // duration in seconds
        
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, duration * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
    [toast dismissWithClickedButtonIndex:0 animated:YES];
});

Using UIAlertViewController for iOS 9 or later

NSString *message = @"Some message...";

UIAlertController *alert = [UIAlertController alertControllerWithTitle:nil
                                                               message:message
                                                        preferredStyle:UIAlertControllerStyleAlert];

[self presentViewController:alert animated:YES completion:nil];

int duration = 1; // duration in seconds

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, duration * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
    [alert dismissViewControllerAnimated:YES completion:nil];
});

Swift 3.2

let message = "Some message..."
let alert = UIAlertController(title: nil, message: message, preferredStyle: .alert)
self.present(alert, animated: true)
    
// duration in seconds
let duration: Double = 5
    
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + duration) {
    alert.dismiss(animated: true)
}