I am writing an application which will do a multiple task simultaneously. One particular task is to do a job once every 200 ms. To achieve this, I am using two methods calling each other. The first method just calls the second and the second method calls the first with a delay using dispatch_after().
After a few iterations(300-400 times) the block in dispatch_after is not executed after 200 ms. It takes ~5-10 seconds before the block is executed. Please let me know the reason for the behaviour(delay). I also tried NSThread (sleepForTimeInterval:) and I am facing the same problem there too.I am stuck. Please help me.
The code is given below.
Screen.h
#import <Foundation/Foundation.h>
@interface Screen : NSObject
-(void) firstMethod;
-(void) secondMethod;
@end
Screen.m
#import "Screen.h"
@implementation Screen
int i=0;
dispatch_queue_t another_queue;
dispatch_time_t pop_time;
-(Screen*) init {
self = [super init];
if (self) {
another_queue = dispatch_queue_create("com.test.timer.2", NULL);
}
return self;
}
-(void) firstMethod {
i++;
NSLog(@"i value : %d",i);
[self secondMethod];
}
-(void) secondMethod {
pop_time = dispatch_time(DISPATCH_TIME_NOW, 200 * NSEC_PER_MSEC);
dispatch_after(pop_time, another_queue, ^(void){
[self firstMethod];
});
}
@end
AppDelegate.h
#import <Cocoa/Cocoa.h>
#import "Screen.h"
@interface AppDelegate : NSObject <NSApplicationDelegate>
@property (assign) IBOutlet NSWindow *window;
@end
AppDelegate.m
#import "AppDelegate.h"
@implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
// Insert code here to initialize your application
Screen* screen = [[Screen alloc] init];
dispatch_queue_t first_queue = dispatch_queue_create("com.test.timer", NULL);
dispatch_block_t blk =^(void) {
[screen firstMethod];
};
dispatch_async(first_queue, blk);
}
@end
