CODEWITHSUNDEEP
objective-ciosxcodetimernstimer
Philip2905
Philip2905

Reputation: 1

Objective C How do I make a timer that counts down from two minutes?

I searched around the internet for an answer but with no luck. I tried 

- (void)viewDidLoad {

[super viewDidLoad];

twoMinTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(timer) userInfo:nil repeats:YES]; }

- (void)timer {
for (int totalSeconds = 120; totalSeconds > 0; totalSeconds--){

timerLabel.text = [self timeFormatted:totalSeconds];

if ( totalSeconds == 0 ) {

   [twoMinTimer invalidate];

   } } }

but it didn't work, the label went from 2.00 to 0.01 when I went to that view and then it just stopped.

Any advice would be greatly appreciated - Philip

Upvotes: 0

Views: 3691

Answers (1)

CodaFi
CodaFi

Reputation: 43330

You're using a one off for loop instead of simply decrementing the total amount of time. Try this:

- (void)viewDidLoad {

    [super viewDidLoad];
    totalSeconds = 120;
    twoMinTimer = [NSTimer scheduledTimerWithTimeInterval:1.0
                                                   target:self
                                                 selector:@selector(timer)
                                                 userInfo:nil
                                                  repeats:YES];
}

- (void)timer {
    totalSeconds--;
    timerLabel.text = [self timeFormatted:totalSeconds];
    if ( totalSeconds == 0 ) {
        [twoMinTimer invalidate];
    } 
}

Declare totalSeconds as an int.

EDIT: My absolute thanks for @JoshCaswell and @MichaelDorst for the suggestions and code formatting respectively. NSTimer is in no way an accurate representation of time, and is definitely not accurate enough for a stopwatch or counter. Instead, NSDate's +dateSinceNow would be a more accurate substitute, or even the progressively lower level CFAbsoluteTimeGetCurrent() and mach_absolute_time() are accurate to sub-milliseconds

Upvotes: 7

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