Can't create two stopwatches [closed] - ios

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I'm trying to create an app where one of the features is the ability to time multiple things at once. I have two UILabels and two UIButtons on a view, and have code to make one label start timing when its respective button is pressed. As you can see from my code, I have two of everything:
#import "ViewController.h"
#interface ViewController ()
#property (weak, nonatomic) IBOutlet UILabel *display;
- (IBAction)startPressed:(id)sender;
#property (weak, nonatomic) IBOutlet UILabel *display2;
- (IBAction)startPressed2:(id)sender;
#end
#implementation ViewController {
bool start;
bool start2;
NSTimeInterval time;
NSTimeInterval time2;
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.display.text = #"0:00";
self.display2.text = #"0:00";
start = false;
start2 = false;
}
-(void) update1 {
if (start == false) {
return;
}
NSTimeInterval currentTime = [NSDate timeIntervalSinceReferenceDate];
NSTimeInterval elapsedTime = currentTime - time;
int minutes = (int)(elapsedTime / 60.0);
int seconds = (int)(elapsedTime = elapsedTime - (minutes * 60));
self.display.text = [NSString stringWithFormat:#"%u:%02u", minutes, seconds];
[self performSelector:#selector(update1) withObject:self afterDelay:0.1];
}
-(void) update2 {
if (start2 == false) {
return;
}
NSTimeInterval currentTime2 = [NSDate timeIntervalSinceReferenceDate];
NSTimeInterval elapsedTime2 = currentTime2 - time2;
int minutes2 = (int)(elapsedTime2 / 60.0);
int seconds2 = (int)(elapsedTime2 = elapsedTime2 - (minutes2 * 60));
self.display2.text = [NSString stringWithFormat:#"%u:%02u", minutes2, seconds2];
[self performSelector:#selector(update2) withObject:self afterDelay:0.1];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)startPressed:(id)sender {
if (start == false) {
start = true;
time = [NSDate timeIntervalSinceReferenceDate];
[sender setTitle:#"Stop" forState:UIControlStateNormal];
[self update1];
}else {
start = false;
[sender setTitle:#"Start" forState:UIControlStateNormal];
}
}
- (IBAction)startPressed2:(id)sender {
if (start2 == false) {
start2 = true;
time2 = [NSDate timeIntervalSinceReferenceDate];
[sender setTitle:#"Stop" forState:UIControlStateNormal];
[self update2];
}else {
start2 = false;
[sender setTitle:#"Start" forState:UIControlStateNormal];
}
}
#end
However, when I run the app, no matter which button I press, the first Label starts counting. Please help, I can't get both timers running at the same time.
Thanks!

Answer 1

Note: The question code has been substantially updated since this answer was first written.
Both update and update2 call the same method:
[self performSelector:#selector(update) withObject:self afterDelay:0.1];
update2 should call:
[self performSelector:#selector(update2) withObject:self afterDelay:0.1];
The best way to avoid errors like these is through good naming, update1 and update2 would tend to avoid this error. Also there is considerable code that could be factored into common menthols ensuring future changes that are common to both timers get made with one code change.
Objective-C uses BOOL with YES and NO as boolean constants not bool with true and false. It generally makes it easier to use the conventions of the system.
Naming is so important as is eliminating duplicate code. Here is a demonstration implementation:
#import "ViewController.h"
#interface ViewController ()
#property (weak, nonatomic) IBOutlet UILabel *display1;
#property (weak, nonatomic) IBOutlet UILabel *display2;
#property (nonatomic) NSTimeInterval time1;
#property (nonatomic) NSTimeInterval time2;
#property (nonatomic, getter = isRunning1) BOOL running1;
#property (nonatomic, getter = isRunning2) BOOL running2;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.display1.text = [self elapsedTimeInterval:0];
self.display2.text = [self elapsedTimeInterval:0];
self.running1 = NO;
self.running2 = NO;
}
-(void) update {
if (self.isRunning1) {
self.display1.text = [self elapsedTimeInterval:self.time1];
}
if (self.isRunning2) {
self.display2.text = [self elapsedTimeInterval:self.time2];
}
if (self.isRunning1 || self.isRunning2) {
[self performSelector:#selector(update) withObject:self afterDelay:0.1];
}
}
- (NSString *)elapsedTimeInterval:(NSTimeInterval)timeInterval {
NSTimeInterval currentTime = [NSDate timeIntervalSinceReferenceDate];
if (timeInterval == 0) {
timeInterval = currentTime;
}
int elapsedTime = currentTime - timeInterval;
int minutes = elapsedTime / 60;
int seconds = elapsedTime % 60;
NSString *displayText = [NSString stringWithFormat:#"%u:%02u", minutes, seconds];
return displayText;
}
- (IBAction)startPressed1:(UIButton *)button {
self.running1 = !self.isRunning1;
if (self.running1 == YES) {
self.time1 = [NSDate timeIntervalSinceReferenceDate];
[self update];
}
[self setTitleOfButton:button state:self.isRunning1];
}
- (IBAction)startPressed2:(UIButton *)button {
self.running2 = !self.isRunning2;
if (self.running2 == YES) {
self.time2 = [NSDate timeIntervalSinceReferenceDate];
[self update];
}
[self setTitleOfButton:button state:self.isRunning2];
}
- (void)setTitleOfButton:(UIButton *)button state:(BOOL)state {
NSString *title = state ? #"Start" : #"Stop";
[button setTitle:title forState:UIControlStateNormal];
}
#end
Note, there are a number of poor practices in this code which I purposely did not address.

Answer 2

Check your xib file, more specifically, check that the connections for display1 and display2 are correct.
It is possible that when copy/pasting your label you mis connected the labels.