How to pass data to viewController without creating its object - ios

Question

I am creating a iOS static library in which user will pass the name of the Viewontroller and some parameters inside the push and I am getting these details in didReceiveRemoteNotification and from here I got a string suppose NSString *vcName = #"ViewController2" and parameter suppose NSString *param1= #"UserName" NSString *param2= #"email" now I want to pass these parameters to the viewController Which name's string is received from push. But I don't want to write #import ViewController2.
I am able to redirect to ViewController2 without importing it but don't know how to pass these parameters to ViewController2
I can redirect to the viewController from the following code.
NSString *vcName = #"ViewController2";
NSString *param1= #"UserName";
NSString *param2= #"user_email";
UIStoryboard * storyboard = [[[UIApplication sharedApplication] keyWindow] rootViewController].storyboard;
UIViewController *vcToOpen = [storyboard instantiateViewControllerWithIdentifier:vcName]];
vcToOpen.modalPresentationStyle =UIModalPresentationFullScreen;
[[[[UIApplication sharedApplication]keyWindow] rootViewController] presentViewController:vcToOpen animated:YES completion:nil];
Now I want to get these two parameter's value in ViewController2. Can anybody help me how to do it. without writing #import ViewController2 because app can has many ViewControllers and vcName can be any of them.

Answer 1

AppDelegate.h
-(NSString *)getEmail;
-(NSString *)getName;
-(void)setEmail:(NSString *)email Name:(NSString *)name;
+(AppDelegate *)sharedAppDelegate;
AppDelegate.m
#interface AppDelegate ()
{
NSString *strEmail, *strName;
}
-(NSString *)getEmail
{
return strEmail;
}
-(NSString *)getName
{
return strName;
}
-(void)setEmail:(NSString *)email Name:(NSString *)name
{
strEmail = email;
strName = name;
}
+(AppDelegate *)sharedAppDelegate
{
return (AppDelegate *)[[UIApplication sharedApplication] delegate];
}
ViewController1.m
#import "AppDelegate.h"
-(void)gotoViewController2
{
[[AppDelegate sharedAppDelegate] setEmail:#"email#gmail.com" Name:#"name1234"];
[self performSegueWithIdentifier:#"segueToViewController2" sender:nil];
}
ViewController2.m
#import "AppDelegate.h"
- (void)viewDidLoad
{
[super viewDidLoad];
NSString *name = [[AppDelegate sharedAppDelegate]getName];
NSString *email = [[AppDelegate sharedAppDelegate]getEmail];
NSLog(#"name = %# and email = %#",name, email); //name = name1234 and email = email#gmail.com
}

Answer 2

Storing values in your app delegate is just messy.
Each one of your UIViewControllers that could be launched from a push notification could conform to a custom 'launch' protocol.
Each UIViewController e.g. 'UIViewController2' would conform to this protocol.
You could write the protocol like this:
#protocol LaunchProtocol <NSObject>
- (void) launchParams:(NSDictionary *)params;
#end
Each UIViewController could conform to this protocol, like so:
#interface ViewController2 : UIViewController <LaunchProtocol>
#end
#implementation ViewController2
- (void) launchParams:(NSDictionary *)params {
}
#end
Your app delegate only needs to know about the protocol, it doesn't care about your UIViewControllers.
When you get a push notification you check if the view controller conforms to the launch protocol.
...
vcToOpen.modalPresentationStyle =UIModalPresentationFullScreen;
if ([vcToOpen conformsToProtocol:#protocol(LaunchProtocol)]) {
UIViewController <LaunchProtocol> *launchController = (UIViewController <LaunchProtocol> *) vcToOpen;
NSDictionary* params = #{ /* create your param dict */ };
[launchController launchParams:params];
}
[[[[UIApplication sharedApplication] keyWindow] rootViewController] presentViewController:vcToOpen animated:YES completion:nil];
...
You would include the information from the push notification in the 'params' dict, and the UIViewController would extract what information it needs from it in launchParams:
- (void) launchParams:(NSDictionary *)params {
NSLog(#"Username: %#", params[#"username"]);
}

Answer 3

Actually you can use Singleton design pattern to achieve this. Create one shared instance class to store the values.
+ (instancetype)sharedInstance
{
static dispatch_once_t once;
static id sharedInstance;
dispatch_once(&once, ^{
sharedInstance = [[self alloc] init];
});
return sharedInstance;
}
create properties inside the manager class which needs to be saved, then access the values from the manager class.