I am a newbie to Swift. I have started a new project with Swift. I am trying to add SecondViewcontroller view as a subview to the FirstViewController. What i am looking is to declare the SecondViewController property for the FirstViewController. Can anyone please suggest the Swift version of the below code
FirstViewController.h
#interface FirstViewController : UIViewController {
IBOutlet UIView *listContainerView;
}
#property (nonatomic, strong) SecondViewController *secondVC;
#end
FirstViewController.m
#import "FirstViewController.h"
#interface FirstViewController ()
#end
#implementation FirstViewController
- (void)viewDidLoad {
[super viewDidLoad];
UIStoryboard *mainStoryBoard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
self.secondVC = (SecondViewController *)[mainStoryBoard instantiateViewControllerWithIdentifier:#"SecondViewController"];
if (![self.secondVC.view isDescendantOfView:self.view]) {
[self addChildViewController:self.secondVC];
self.secondVC.view.frame = CGRectMake(0, 0, listContainerView.frame.size.width, listContainerView.frame.size.height);
[listContainerView addSubview:self.secondVC.view];
[self.secondVC didMoveToParentViewController:self];
}
}
#end
What you should do is to make a subview, instead of making a new UIViewController. In only very special cases would you ever put one UIViewController inside another. Basically every 'screen' should have one UIViewController, but you shouldn't put one inside another.
Related
I have two view controllers used in a Tab Bar Controller: FirstViewController and SecondViewController. I'm trying to call a method in the SecondViewController from the FirstViewController, but do this before the SecondViewController is loaded by selecting the Second Tab. Is this possible? I've tried notifications and delegates and can't seem to get it to work, unless I select the SecondViewController and run ViewDidLoad first, and then call it from the FirstViewController.
This is in objective-c and I'm trying to call setAutoModeTimer() in the SecondViewController.
Here is my code:
FirstViewController.h
#import <UIKit/UIKit.h>
#protocol FirstViewControllerDelegate <NSObject>
- (void) setAutoModeTimer;
#end
#interface FirstViewController : UIViewController
#property (nonatomic,weak) id <FirstViewControllerDelegate> delegate;
#end
FirstViewController.m
#import "FirstViewController.h"
#import "SecondViewController.h"
#interface FirstViewController ()
#end
#implementation FirstViewController
- (void)viewDidLoad {
[super viewDidLoad];
SecondViewController * myViewController = [[SecondViewController alloc] init];
[myViewController view];
// Do any additional setup after loading the view, typically from a nib.
}
//- (void)loadView{[self.tabBarController.viewControllers makeObjectsPerformSelector:#selector(view)];}
- (IBAction)startTimerButtonPressed:(id)sender {
[self.delegate setAutoModeTimer];
}
#end
SecondViewController.h
#import <UIKit/UIKit.h>
#interface SecondViewController : UIViewController
#end
SecondViewController.m
#import "SecondViewController.h"
#import "FirstViewController.h"
#interface SecondViewController () <FirstViewControllerDelegate>
#end
#implementation SecondViewController
- (void)viewDidLoad {
[super viewDidLoad];
FirstViewController *firstVC = [self.storyboard instantiateViewControllerWithIdentifier:#"FirstViewController"];
firstVC.delegate = self;
}
- (void) setAutoModeTimer
{
NSLog(#"Timer has started");
}
#end
You don't need to keep references in each view controller for another one. What are you doing is creating new instances of UIViewControllers in each view controller.
FirstViewController *firstVC = [self.storyboard instantiateViewControllerWithIdentifier:#"FirstViewController"];
firstVC.delegate = self;
After viewDidLoad will be finished firstVC instance will be released.
Because you created a local var. It is not the same viewController you have in tabBar.
You need to setup connection between view controllers once.
It can be done by setup your UITabBarController programmatically, not in stroryboard.
You can setup viewControllers of UITabBarController once, and setup connections between them.
#import "SecondViewController.h"
#import "FirstViewController.h"
#implementation MainTabBarController
- (void)viewDidLoad {
[super viewDidLoad];
NSMutableArray *listOfViewControllers = [[NSMutableArray alloc] init];
FirstViewController *firstVC = [self.storyboard instantiateViewControllerWithIdentifier:#"FirstViewController"];
SecondViewController * secondVC = [[SecondViewController alloc] init];
firstVC.delegate = secondVC;
[listOfViewControllers addObject:firstVC];
[listOfViewControllers addObject:secondVC];
[self setViewControllers:listOfViewControllers
animated:YES];
}
I'd like to trigger a message from viewController to another viewController.
And I coded like below, but viewController didn't call delegate.
I want to call delegate without stroyboard. I just want to send a message to another viewController.
viewController2.h
#protocol ViewController2Delegate;
#interface ViewController2 : UIViewController
#property (nonatomic, weak) id<ViewController2Delegate> delegate;
#end
#protocol ViewController2Delegate <NSObject>
- (void)showSomethingByDelegate;
#end
viewController2.m
#import "ViewController2.h"
#interface ViewController2 ()
#end
#implementation ViewController2
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
}
- (IBAction)buttonPressed:(id)sender {
[self.delegate showSomethingByDelegate];
}
#end
viewController.m
#import "ViewController.h"
#import "ViewController2.h"
#interface ViewController ()
<ViewController2Delegate>
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
ViewController2 *vc2 = [[ViewController2 alloc] init];
vc2.delegate = self;
}
// Below method was not called by delegate.
- (void)showSomethingByDelegate {
NSLog(#"Button Was Pressed!!!");
}
#end
well let me show an example more simple.
File: firstVC.h
/* This define the protocol object,
you can write methods required or optional the diference is when
the protocol is used in a class, xcode show you a yellow warning with required methods
like UITableViewDelegate, UITextFieldDelegate... */
#protocol firstVCDelegate <NSObject>
#required
- (void)didMessageFromOtherViewController: (NSString *)messageStr;
#optional
- (void)didOtherMessageNotRequired: (NSString *)messageStr;
#end
/* This is the definition of first UIViewController */
#interface firstViewController : UIViewController
#end
/* This is the definition of second UIViewController object with
a property that is our protocol 'firstVCDelegate' */
#interface secondViewController : UIViewController
#property (nonatomic, weak) id <firstVCDelegate> firstVCDelegate;
- (void)executeDelegateProcess;
#end
File: firstVC.m
#import "firstVC.h"
#pragma mark - First UIViewController with delegate
#interface firstViewController() <firstVCDelegate>
#end
#implementation firstViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Creating the 'secondViewController' object with delegate on this class
secondViewController *svc = [secondViewController new];
// Assign the delegate class
[svc setFirstVCDelegate: self];
// Run the delegate logic
[svc executeDelegateProcess];
}
- (void)didMessageFromOtherViewController:(NSString *)messageStr
{
// Receiving the message from the instance of our protocol in the 'secondViewController' class
NSLog(#"MESSAGE #1: %#", messageStr);
}
- (void)didOtherMessageNotRequired:(NSString *)messageStr
{
// Receiving the message in optional method
NSLog(#"MESSAGE #2: %#", messageStr);
}
#end
#pragma mark - Second UIViewController
#implementation secondViewController
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (void)setFirstVCDelegate:(id<firstVCDelegate>)firstVCDelegate
{
if (firstVCDelegate)
_firstVCDelegate = firstVCDelegate;
}
- (void)executeDelegateProcess
{
// This method is only for demo
// You can execute your delegate in the way you need to use
if (_firstVCDelegate) {
[_firstVCDelegate didMessageFromOtherViewController: #"Hello world, using the required method from secondViewController class"];
[_firstVCDelegate didOtherMessageNotRequired: #"Hello code using the optional method"];
}
}
#end
In your appDelegate.m in the method didFinishLaunchingWithOptions you can put this, and you need to #import "firstVC.h"
self.window = [[UIWindow alloc] initWithFrame: [[UIScreen mainScreen] bounds]];
self.window.autoresizesSubviews = YES;
[self.window makeKeyAndVisible];
[_window setRootViewController: [firstViewController new]];
Execute and see two logs messages, I hope I've helped :)
ViewController2 *vc2 = [[ViewController2 alloc] init];
This line of code is not doing what you think it is, this is creating a NEW instance of ViewController2 and storing it inside the variable vc2. At no point (based on your code) is this variable added to the navigation stack and displayed on screen.
Edit
Also as noticed by Holex, your vc2 variable will be removed from memory after the viewDidLoad is finished as you are not holding onto a reference of it. You would either need to create a property to hold onto it, or push it onto the navigation stack for the navigationController to hold onto it.
There are multiple ways to solve this issue:
Instead of creating a new viewController2, find a reference to the one already displayed on the screen (if it is on the screen).
If its not on the navigation stack, add vc2 to the navigation stack [self.navigationController pushViewController:vc2 animated:YES]; (assuming you have a navigation controller).
If not on the stack, and not intending to use a navigationController, present vc2 modally, such as [self presentViewController:vc2 animated:YES completion:nil];
I am trying to send string from Second VC to First VC. I have assigned delegate to first VC and given protocol in second VC but I don't see the method in First VC is being called when Second VC sends some data.
Code
First VC
FirstViewController.h
#import <UIKit/UIKit.h>
#import "SecondViewController.h"
#interface FirstViewController : UIViewController <cellDelegate>
#end
FirstViewController.m
- (void)printString:(NSString *)string{
NSLog(#"Received string: %#",string);
}
SecondViewController.h
#protocol cellDelegate <NSObject>
- (void)printString:(NSString *)string{
#end
#interface SecondViewController : UIViewController
#property (nonatomic, weak) id <cellDelegate> delegate;
#end
SecondViewController.m
- (IBAction)buttonPressed:(id)sender {
if ([self.delegate respondsToSelector:#selector(printString:)]) {
[self.delegate printString:#"arrow"]];
}
}
Any help is greatly appreciated.
You forgot to do
SecondViewcontroller *vc;
vc.delegate=self;
On first view controller
Maybe you just forgot to assign your secondViewController.delegate to self.
1- In first viewController, before pushing secondViewController, with that SecondViewController instance do:
secondViewController.delegate = self;
I can not comment, so if this does not work out just let me know or share more code.
When you navigate from one VC to Second VC you can set the delegate.
SecondViewcontroller *secondVC = [self.storyboard instantiateViewControllerWithIdentifier:#"SecondViewcontroller"];
secondVC.delegate = self;
[self.navigationController pushViewController:secondVC animated:YES];
This code writes on FirstViewController. Hope it helps you.
In a view, let's call it firstView I created a secondView as follows and pushed it if certain thing happened in the firstView:
SecondViewController *secondVC = [[secondViewController alloc] initWithNibName:#"SecondViewController" bundle:nil];
[self.navigationController pushViewController:secondVC animated:YES];
[secondVC release];
Now when I'm in the secondView if let say a button is pressed I want to go back to firstView and also pass back a value from secondView to the firstView (let say an integer value of a textfield from secondView to the firstView).
Here is what I tried:
#protocol SecondViewControllerDelegate;
#import <UIKit/UIKit.h>
#import "firstViewController.h"
#interface SecondViewController : UIViewController <UITextFieldDelegate>
{
UITextField *xInput;
id <SecondViewControllerDelegate> delegate;
}
- (IBAction)useXPressed:(UIButton *)sender;
#property (assign) id <SecondViewControllerDelegate> delegate;
#property (retain) IBOutlet UITextField *xInput;
#end
#protocol SecondViewControllerDelegate
- (void)secondViewController:(SecondViewController *)sender xValue:(int)value;
#end
And in the m file
- (IBAction)useXPressed:(UIButton *)sender
{
[self.delegate secondViewController:self xValue:1234]; // 1234 is just for test
}
And then in the firstView I did:
#import "SecondViewController.h"
#interface FirstViewController : UITableViewController <SecondViewControllerDelegate> {
}
#end
And implemented:
- (void) secondViewController:(SecondViewController *)sender xValue:(int)value
{
[self.navigationController popViewControllerAnimated:YES];
}
Now, the problem is for one in FirstViewController I get the warning that "No definition of protocol "SecondViewControllerDelegate" is found, and for two the delegate method (last piece of code above) does not get invoked at all. Can somebody please tell me what's wrong?
After this line
SecondViewController *secondVC = [[secondViewController alloc] initWithNibName:#"SecondViewController" bundle:nil];
Add
secondVC.delegate = self;
Also instead of
- (void) secondViewController:(SecondViewController *)sender xValue:(int)value
{
[self.navigationController popViewControllerAnimated:YES];
}
You should use
- (void) secondViewController:(SecondViewController *)sender xValue:(int)value
{
[sender popViewControllerAnimated:YES];
}
In FirstViewController .h file :
#import "SecondViewController.h"
#interface FirstViewController : UITableViewController <SecondViewControllerDelegate> {
SecondViewController *secondViewController;
}
#end
In implementation file , where you init SecondViewController instance next line assign self to delegate property :
secondViewController.delegate = self;
Next define delegate method :
- (void)secondViewController:(SecondViewController *)sender xValue:(int)value
{
NSLog ("This is a Second View Controller with value %i",value)
}
For problem 1: The #protocol definition for SecondViewControllerDelegate looks like it's in secondViewController.h; are you sure this file is imported in firstViewController.h? Otherwise it won't know about the protocol.
Problem 2: It might be totally unrelated to problem 1. Are you sure the action is hooked up properly? Can you put a NSLog() call in your useXPressed: to make sure that method is actually getting called when you expect it to?
so, I need to send data backwards when poping two views. I tried using protocol, so this is part of my code:
RootViewController.h
#import <UIKit/UIKit.h>
#import "ThirdViewController.h"
#class SecondViewController;
#interface RootViewController : UIViewController <PassInt>
#property (strong, nonatomic) SecondViewController *secondViewController;
#property (strong, nonatomic) ThirdViewController *thirdViewController;
#property (nonatomic) int intNumber;
#end
RootViewController.m
#import "RootViewController.h"
#import "SecondViewController.h"
#implementation RootViewController
#synthesize secondViewController = _secondViewController;
#synthesize thirdViewController = _thirdViewController;
#synthesize intNumber = _intNumber;
- (void)setIntNumber:(int)number{
_intNumber = number;
}
#pragma mark - View lifecycle
- (void)viewWillAppear:(BOOL)animated {
if(!_thirdViewController){
_thirdViewController = [[ThirdViewController alloc] initWithNibName:#"ThirdViewController" bundle:[NSBundle mainBundle]];
}
if(!_secondViewController){
_secondViewController = [[SecondViewController alloc] initWithNibName:#"SecondViewController" bundle:[NSBundle mainBundle]];
self.secondViewController.thirdViewController = self.thirdViewController;
}
[self.navigationController pushViewController:self.secondViewController animated:YES];
}
#end
SecondViewController.h
#import <UIKit/UIKit.h>
#class ThirdViewController;
#interface SecondViewController : UIViewController
#property (strong, nonatomic) ThirdViewController *thirdViewController;
#end
SecondViewController.m
#import "SecondViewController.h"
#import "ThirdViewController.h"
#implementation SecondViewController
#synthesize thirdViewController = _thirdViewController;
...
-(void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex{
[self.navigationController pushViewController:self.userPreferencesViewController animated:YES];
}
#end
ThirdViewController.h
#import <UIKit/UIKit.h>
#protocol PassInt <NSObject>
#required
- (void) setIntNumber:(int)number;
#end
#interface ThirdViewController : UIViewController{
id <PassInt> delegate;
}
#property (retain) id delegate;
- (IBAction)saveChanges;
#end
ThirdViewController.m
#import "ThirdViewController.h"
#implementation ThirdViewController
- (IBAction)saveChanges{
int someInt = 3;
[[self delegate] setIntNumber:someInt];
UINavigationController *tempNavigationController = self.navigationController;
[tempNavigationController popViewControllerAnimated:NO];
[tempNavigationController popViewControllerAnimated:NO];
}
...
#end
I would appreciate any help!
In the UINavigationController reference check the property call :
#property(nonatomic, copy) NSArray *viewControllers
Discussion
The root view controller is at index 0 in the array, the back view controller is at index n-2, and the top controller is at index n-1, where n is the number of items in the array.
That could give you a handle to the rootViewController.
Would that be a good solution for you?
There is other ways. But from your comment I think that could be a match.
[[self.navigationController viewControllers] objectAtIndex:0].someProerty;
Another method could be to use NSNotifications. Have the RootViewController resgister as an observer for a notification posted by the ThirdViewController. Then in the userInfo dictionary of the notification posted by the ThirdViewController, you pass someInt as an NSNumber.
This provides sufficient abstraction because your ThirdViewController doesn't need to know what kind of object requires the information, it is just posting it so interested observers know about it.
Good Luck
You're never assigning anything to the delegate member of your ThirdViewController in the code you posted. Also, delegates should usually be assign, not retain.