IOS response button click in another viewController - ios

Question

Here is the main idea
+---MyViewController.m----+ +---BtnOnClickResp.m-----+
| | EventTouchUpInside: | |
| Button ---------------------------------------> OnBtnClick() |
| | textView.text=#"blabla"| | |
| *textView <------------------------------------------ + |
| | | |
+-------------------------+ +------------------------+
I want to test if button OnClick could be pressed in another controller like this:
MyViewController.h
#import <UIKit/UIKit.h>
#interface MyViewController : UIViewController
#property (nonatomic, strong) UITextView *textView;
+(id) sharedInstance;
#end
MyViewController.m
#import "MyViewController.h"
#import "BtnOnClickResp.h"
#interface MyViewController ()
#end
#implementation MyViewController
#synthesize textView;
+ (id) sharedInstance{
static MyViewController *instance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[self alloc] init];
});
return instance;
}
- (void) setUpScene{
textView = [[UITextView alloc] initWithFrame:CGRectMake(0, 0, 500, 400) ];
[textView setBackgroundColor:[UIColor grayColor]];
[textView setFont:[UIFont systemFontOfSize:18]];
[textView setTextColor:[UIColor blackColor]];
textView.text = #"";
[self.view addSubview:textView];
UIButton *btn = [[UIButton alloc] initWithFrame:CGRectMake(100, 50 , 400, 50)];
[btn setTitle:#"Click Me" forState:UIControlStateNormal];
[btn setBackgroundColor:[UIColor yellowColor]];
[btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[btn addTarget:[[BtnOnClickResp alloc] init] action:#selector(onBtnClick:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:btn];
}
- (void)viewDidLoad {
[super viewDidLoad];
[self setUpScene];
// Do any additional setup after loading the view.
}
#end
BtnOnClickResp.h
#import <UIKit/UIKit.h>
#interface BtnOnClickResp : UIViewController
#end
BtnOnClickResp.m
#import "BtnOnClickResp.h"
#import "MyViewController.h"
#interface BtnOnClickResp ()
#end
#implementation BtnOnClickResp
- (void) onBtnClick: (UIButton *) btn{
NSLog(#"btn was click but I am in another controller");
MyViewController *control = [MyViewController sharedInstance];
control.textView.text = #" I am setting this content in another view cheers!!!";
}
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
The main idea is draw/add a button view in the MyViewController and make the response to click code in another controller, I thought the action assignment code:
[btn addTarget:self action:#selector(onBtnClick:) forControlEvents:UIControlEventTouchUpInside];
if we change the self to the actually controller we want to use then the click event will be dispatched to that controller
But it seems not working.
Really a beginner of ios development would be happy if you don't downvote this beginner's question.
EIDT
After taking the advice as #Mike suggested,
I change the MyViewController.m to this:
#import "MyViewController.h"
#import "BtnOnClickResp.h"
#interface MyViewController (){
//here is the change , I made a private ref of the controller
BtnOnClickResp *respContl;
}
#end
#implementation MyViewController
#synthesize textView;
+ (id) sharedInstance{
static MyViewController *instance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[self alloc] init];
});
return instance;
}
- (void) setUpScene{
textView = [[UITextView alloc] initWithFrame:CGRectMake(0, 0, 500, 400) ];
[textView setBackgroundColor:[UIColor grayColor]];
[textView setFont:[UIFont systemFontOfSize:18]];
[textView setTextColor:[UIColor blackColor]];
textView.text = #"";
[self.view addSubview:textView];
UIButton *btn = [[UIButton alloc] initWithFrame:CGRectMake(100, 50 , 400, 50)];
[btn setTitle:#"Click Me" forState:UIControlStateNormal];
[btn setBackgroundColor:[UIColor yellowColor]];
[btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[btn addTarget:respContl action:#selector(onBtnClick:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:btn];
}
- (void)viewDidLoad {
respContl = [[BtnOnClickResp alloc] init];
[super viewDidLoad];
[self setUpScene];
// Do any additional setup after loading the view.
}
#end
Now I could see the NSLog of btn was click but I am in another controller but the view content still kept not changed to #" I am setting this content in another view cheers!!!" as it expected to be in BtnOnClickResp.m
This is the launch code in AppDelagate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
UIViewController *control = [[MyViewController alloc] init];
[self.window setRootViewController:control];
[self.window setBackgroundColor:[UIColor greenColor]];
[self.window makeKeyAndVisible];
// Override point for customization after application launch.
return YES;
}

Answer 1

You are adding Target
[btn addTarget:[[BtnOnClickResp alloc] init] action:#selector(onBtnClick:) forControlEvents:UIControlEventTouchUpInside];
to
[BtnOnClickResp alloc] init]
is Wrong
Because it will create new instance and add listener to it.
However you are try to access action in other instance
You have 4 solutions
Create shared instance of BtnOnClickResp and assign target to it
Pass the self of BtnOnClickResp to the MyViewController on and assign it
Create Delegate
Post Notification

Answer 2

Declare a property of BtnOnClickResp and set it as button target.
#import "MyViewController.h"
#import "BtnOnClickResp.h"
#interface MyViewController ()
#property(nonatomic, strong) BtnOnClickResp onClickRespObj;
#end
#implementation MyViewController
#synthesize textView;
+ (id) sharedInstance{
static MyViewController *instance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[self alloc] init];
});
return instance;
}
- (id)init{
if(self = [super init]){
self.onClickRespObj = [[BtnOnClickResp alloc] init];
}
return self;
}
- (void) setUpScene{
textView = [[UITextView alloc] initWithFrame:CGRectMake(0, 0, 500, 400) ];
[textView setBackgroundColor:[UIColor grayColor]];
[textView setFont:[UIFont systemFontOfSize:18]];
[textView setTextColor:[UIColor blackColor]];
textView.text = #"";
[self.view addSubview:textView];
UIButton *btn = [[UIButton alloc] initWithFrame:CGRectMake(100, 50 , 400, 50)];
[btn setTitle:#"Click Me" forState:UIControlStateNormal];
[btn setBackgroundColor:[UIColor yellowColor]];
[btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[btn addTarget:self.onClickRespObj action:#selector(onBtnClick:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:btn];
}
- (void)viewDidLoad {
[super viewDidLoad];
[self setUpScene];
// Do any additional setup after loading the view.
}
#end