1.GCD设置一个timer计时器
- (void)awakeFromNib {
__weak id weakSelf = self;
double delayInSeconds = 0.25;
_timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,dispatch_get_main_queue());
dispatch_source_set_timer(_timer, dispatch_walltime(NULL, 0),(unsigned)(delayInSeconds * NSEC_PER_SEC), 0);
dispatch_source_set_event_handler(_timer, ^{
[weakSelf updateValues];
});
dispatch_resume(_timer);
}
- (void)updateValues {
}
- (void)dealloc {
dispatch_source_cancel(_timer);
}