IOS countdown and iOS countdown

IOS countdown and iOS countdown

Method 1: Use NSTimer (applicable to message Verification Code countdown)

The NSTimer scheduledTimerWithTimeInterval method is used to execute the changeTime method once per second.

// Create a Timer and execute changeTime every second: Method

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

// ChangeTime

-(Void) changeTime :( nstmer *) timer

{

// Click btn to obtain the verification code

UIButton * button = (UIButton *) [self. view viewWithTag: 99];

If (count = 0 ){

// Invalidate after completion

[Timer invalidate];

// 59s countdown

Count = 59;

[Button setTitle: @ "re-obtain" forState: UIControlStateNormal];

Button. userInteractionEnabled = YES;

Button. alpha = 1;

}

Else {

[Button setTitle: [NSString stringWithFormat: @ "% d s", count] forState: UIControlStateNormal];

Count --;

}

}

 

Method 2: GCD is used for implementation (compared to the countdown of a seller to a certain activity)

In the. h file, define a Timer to control the time.

// Countdown Timer

Dispatch_source_t _ timer;

 

Implementation in the. m file:

// Create a timestamp

NSDateFormatter * dateFormatter = [[NSDateFormatter alloc] init];

// Timestamp format

[DateFormatter setDateFormat: @ "yyyy/MM/dd HH: mm: ss"];

// Convert NSString data of the same timestamp format to NSDate data

NSDate * endDate = [dateFormatter dateFromString: _ EndTime];

NSDate * startDate = [dateFormatter dateFromString: _ StartTime];

NSDate * currentDate = [dateFormatter dateFromString: _ CurrentTime];

// Calculate the timestamp of the current server time from the end of the activity

NSTimeInterval timeInterval = [endDate timeIntervalSinceDate: currentDate];

// Calculate the timestamp of the current server time and Activity start time.

NSTimeInterval StartToNow = [currentDate timeIntervalSinceDate: startDate];

// Countdown time

_ Block int timeout = timeInterval;

_ Block int StartTimeout = StartToNow;

If (timeout! = 0 ){

Dispatch_queue_t queue = dispatch_get_global_queue (DISPATCH_QUEUE_PRIORITY_DEFAULT, 0 );

// Parallel queue

// The parallel queue can process multiple tasks at the same time. You can use dispatch_queue_create to create a parallel queue, but we usually use the predefined parallel queue, that is, Global Queue (Global // Concurrent Dispatch Queues ). Currently, the system predefines four global Queues with different running priorities. We can obtain them through dispatch_get_global_queue.

// The first parameter of dispatch_get_global_queue is the queue priority, which corresponds to four global queues respectively:

// DISPATCH_QUEUE_PRIORITY_HIGH

// DISPATCH_QUEUE_PRIORITY_DEFAULT

// DISPATCH_QUEUE_PRIORITY_LOW

// DISPATCH_QUEUE_PRIORITY_BACKGROUND

 

// The second parameter in dispatch_get_global_queue is currently retained by the system. Set it to 0.

 

// Execution per second

_ Timer = dispatch_source_create (DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue );

Dispatch_source_set_timer (_ timer, dispatch_wall time (NULL, 0), 1.0 * NSEC_PER_SEC, 0 );

Dispatch_source_set_event_handler (_ timer, ^ {

// The countdown is over and off

If (timeout <= 0 | StartTimeout <= 0 ){

Dispatch_source_cancel (_ timer );

_ Timer = nil;

 

// Run the task in the queue

// You can add a new task to a queue at any time. You only need to call dispatch_async:

Dispatch_async (dispatch_get_main_queue (), ^ {

// You can design the content, display format, and style to be displayed as needed.

DayLabel. text = @ "0 days ";

HourLabel. text = @ "00 :";

MinLabel. text = @ "00 :";

SecLabel. text = @ "00 ";

Label. text = @ "The Flash sale is over !!! ";

});

} Else {

Label. text = @ "Remaining Time for flash sale :";

Int days = (int) (timeout/(3600*24 ));

If (days = 0 ){

DayLabel. text = @"";

}

Int hours = (int) (timeout-days * 24*3600)/3600 );

Int minute = (int) (timeout-days * 24*3600-hours * 3600)/60;

Int second = timeout-days x 24*3600-hours * 3600-minute * 60;

Dispatch_async (dispatch_get_main_queue (), ^ {

If (days = 0 ){

DayLabel. text = @ "0 days ";

} Else {

DayLabel. text = [NSString stringWithFormat: @ "% d days", days];

}

If (hours <10 ){

HourLabel. text = [NSString stringWithFormat: @ "0% d:", hours];

} Else {

HourLabel. text = [NSString stringWithFormat: @ "% d:", hours];

}

If (minute <10 ){

MinLabel. text = [NSString stringWithFormat: @ "0% d:", minute];

} Else {

MinLabel. text = [NSString stringWithFormat: @ "% d:", minute];

}

If (second <10 ){

SecLabel. text = [NSString stringWithFormat: @ "0% d", second];

} Else {

SecLabel. text = [NSString stringWithFormat: @ "% d", second];

}

});

Timeout --;

}

});

Dispatch_resume (_ timer );

}