How to have two buttons change title and do two different functions? - ios

Question

I'm using Objective-C to make a stopwatch. I already have a basic stop watch with 3 buttons: Start, Stop and reset. Here is my code for viewcontroller.m:
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
-(IBAction)Start:(id)start
{
Timer = [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:#selector(addingthetime) userInfo:nil repeats:YES];
}
-(IBAction)Stop:(id)sender
{
[Timer invalidate];
}
-(IBAction)Restart:(id)sender
{
[Timer invalidate];
addingtheTime = 0;
Label.text = [NSString stringWithFormat:#"0.00"];
}
-(void)addingthetime
{
addingtheTime = addingtheTime + 0.01;
Label.text = [NSString stringWithFormat:#"%.2f", addingtheTime];
}
#end
And here is my code for viewcontroller.h:
#import <UIKit/UIKit.h>
float addingtheTime;
#interface ViewController : UIViewController
{
IBOutlet UILabel *Label;
NSTimer *Timer;
}
#end
So my question is how do I make the Start button do the following once clicked:
Start the timer
Change the title to stop
(Click the same button again)
Stop the timer
Change the title to start
So the aim is to have only one button which starts and stops the timer but please I want the title to change as well.
Don't worry about the reset button as I want that to remain by itself.
PS. Please explain things clearly because I find it really hard to understand some things and I am a beginner so try and keep it fairly simple thanks, and sorry if the question isn't clear.

Answer 1

You can use button.tag property to achieve this. By Default the button.tag property have 0. So assume that 0 is a state when timer is Not started and 1 is the state when timer is started. You can manipulate .tag property according to your custom logic.
-(IBAction)Start:(id)start
{
UIButton *button = (UIButton *)start;
if (button.tag == 0){
button.tag = 1;
[button setTitle:#"Stop" forControlState:UIControlStateNormal];
Timer = [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:#selector(addingthetime) userInfo:nil repeats:YES];
}else {
button.tag = 0;
[button setTitle:#"Stop" forControlState:UIControlStateNormal];
//Invoke your method to stop Timer.
}
}

Answer 2

In the ViewController.h:
#import <UIKit/UIKit.h>
float addingtheTime;
#interface ViewController : UIViewController
{
IBOutlet UILabel *Label;
NSTimer *Timer;
}
#end
In the ViewController.m:
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
-(void)addingthetime
{
addingtheTime = addingtheTime + 0.01;
Label.text = [NSString stringWithFormat:#"%.2f", addingtheTime];
}
- (IBAction)startOrStopAction:(UIButton *)sender {
// stop
if ([sender.titleLabel.text isEqualToString:#"stop"]) {
[Timer setFireDate:[NSDate distantFuture]];
[sender setTitle:#"start" forState:UIControlStateNormal];
}
// start
else {
if (!Timer) {
Timer = [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:#selector(addingthetime) userInfo:nil repeats:YES];
}else {
[Timer setFireDate:[NSDate date]];
}
[sender setTitle:#"stop" forState:UIControlStateNormal];
}
}
#end
The result:
In iPhone:
In iPad: