CFRunLoopTimerRef¶
CFRunLoopTimerRef：基于时间的触发器，CFRunLoopTimerRef是Core Foundation提供的基础定时器，NSTimer则是建立在CFRunLoopTimerRef之上的高层组件。
当Timer被加入到RunLoop时，RunLoop会注册对应的时间点，当达到时间时，RunLoop会被唤醒，执行创建Timer时的回调。
// 创建一个每秒触发一次的定时器
let timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { timer in
print("Timer fired!")
// 你的代码...
}
控制台bt可以看到堆栈流程
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
* frame #0: 0x000000010ba30243 01-Runloop初探`__28-[ViewController sourceDemo]_block_invoke(.block_descriptor=0x000000010ba320a8, timer=0x000060000091c240) at ViewController.m:32:9
frame #1: 0x00007fff2085e951 Foundation`__NSFireTimer + 67
frame #2: 0x00007fff2039178a CoreFoundation`CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION + 20
frame #3: 0x00007fff2039127c CoreFoundation`__CFRunLoopDoTimer + 924
frame #4: 0x00007fff2039081a CoreFoundation`__CFRunLoopDoTimers + 265
frame #5: 0x00007fff2038ae69 CoreFoundation`__CFRunLoopRun + 2013
frame #6: 0x00007fff2038a1a7 CoreFoundation`CFRunLoopRunSpecific + 567
frame #7: 0x00007fff2b874d85 GraphicsServices`GSEventRunModal + 139
frame #8: 0x00007fff246c14df UIKitCore`-[UIApplication _run] + 912
frame #9: 0x00007fff246c639c UIKitCore`UIApplicationMain + 101
frame #10: 0x000000010ba30451 01-Runloop初探`main(argc=1, argv=0x00007ffee41cfc60) at main.m:21:16
frame #11: 0x00007fff2025abbd libdyld.dylib`start + 1
(lldb)
CFRunLoopAddTimer¶
把timer加到runloop
void CFRunLoopAddTimer(CFRunLoopRef rl, CFRunLoopTimerRef rlt, CFStringRef modeName) {
CHECK_FOR_FORK();
if (__CFRunLoopIsDeallocating(rl)) return;
if (!__CFIsValid(rlt) || (NULL != rlt->_runLoop && rlt->_runLoop != rl)) return;
__CFRunLoopLock(rl);
if (modeName == kCFRunLoopCommonModes) {
CFSetRef set = rl->_commonModes ? CFSetCreateCopy(kCFAllocatorSystemDefault, rl->_commonModes) : NULL;
if (NULL == rl->_commonModeItems) {
rl->_commonModeItems = CFSetCreateMutable(kCFAllocatorSystemDefault, 0, &kCFTypeSetCallBacks);
}
CFSetAddValue(rl->_commonModeItems, rlt);
if (NULL != set) {
CFTypeRef context[2] = {rl, rlt};
/* add new item to all common-modes */
//设置回调函数
CFSetApplyFunction(set, (__CFRunLoopAddItemToCommonModes), (void *)context);
CFRelease(set);
}
} else {
//根据mode名字找到mode
CFRunLoopModeRef rlm = __CFRunLoopFindMode(rl, modeName, true);
//如果没有 就创建一个
if (NULL != rlm) {
if (NULL == rlm->_timers) {
CFArrayCallBacks cb = kCFTypeArrayCallBacks;
cb.equal = NULL;
rlm->_timers = CFArrayCreateMutable(kCFAllocatorSystemDefault, 0, &cb);
}
}
if (NULL != rlm && !CFSetContainsValue(rlt->_rlModes, rlm->_name)) {
__CFRunLoopTimerLock(rlt);
if (NULL == rlt->_runLoop) {
rlt->_runLoop = rl;
} else if (rl != rlt->_runLoop) {
__CFRunLoopTimerUnlock(rlt);
__CFRunLoopModeUnlock(rlm);
__CFRunLoopUnlock(rl);
return;
}
CFSetAddValue(rlt->_rlModes, rlm->_name);
__CFRunLoopTimerUnlock(rlt);
__CFRunLoopTimerFireTSRLock();
__CFRepositionTimerInMode(rlm, rlt, false);
__CFRunLoopTimerFireTSRUnlock();
if (!_CFExecutableLinkedOnOrAfter(CFSystemVersionLion)) {
// Normally we don't do this on behalf of clients, but for
// backwards compatibility due to the change in timer handling...
if (rl != CFRunLoopGetCurrent()) CFRunLoopWakeUp(rl);
}
}
if (NULL != rlm) {
__CFRunLoopModeUnlock(rlm);
}
}
__CFRunLoopUnlock(rl);
}
执行timer¶
- timer依赖mode去run
- runloop run的时候：
- 遍历timers
- __CFRunLoopDoTimer
- 根据mode拿到runloop中的timer
- 执行回调
__CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__
// rl and rlm are locked on entry and exit
static Boolean __CFRunLoopDoTimers(CFRunLoopRef rl, CFRunLoopModeRef rlm, uint64_t limitTSR) { /* DOES CALLOUT */
Boolean timerHandled = false;
CFMutableArrayRef timers = NULL;
//先找到runloop里的所有timer，可能不止一个
for (CFIndex idx = 0, cnt = rlm->_timers ? CFArrayGetCount(rlm->_timers) : 0; idx < cnt; idx++) {
CFRunLoopTimerRef rlt = (CFRunLoopTimerRef)CFArrayGetValueAtIndex(rlm->_timers, idx);
if (__CFIsValid(rlt) && !__CFRunLoopTimerIsFiring(rlt)) {
if (rlt->_fireTSR <= limitTSR) {
if (!timers) timers = CFArrayCreateMutable(kCFAllocatorSystemDefault, 0, &kCFTypeArrayCallBacks);
CFArrayAppendValue(timers, rlt);
}
}
}
//遍历 执行。__CFRunLoopDoTimer
for (CFIndex idx = 0, cnt = timers ? CFArrayGetCount(timers) : 0; idx < cnt; idx++) {
CFRunLoopTimerRef rlt = (CFRunLoopTimerRef)CFArrayGetValueAtIndex(timers, idx);
Boolean did = __CFRunLoopDoTimer(rl, rlm, rlt);
timerHandled = timerHandled || did;
}
if (timers) CFRelease(timers);
return timerHandled;
}
NSTimer相关代码¶
/*
（1）runloop一启动就会选中一种模式，当选中了一种模式之后其它的模式就都不管了。一个mode里面可以添加多个NSTimer,也就是说以后当创建NSTimer的时候，可以指定它是在什么模式下运行的。
（2）它是基于时间的触发器，说直白点那就是时间到了就触发一个事件，触发一个操作。基本上说的就是NSTimer
*/
- (void)timer2
{
//NSTimer 调用了scheduledTimer方法，那么会自动添加到当前的runloop里面去，而且runloop的运行模式kCFRunLoopDefaultMode
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(run) userInfo:nil repeats:YES];
//更改模式
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
}
- (void)timer1
{
NSTimer *timer = [NSTimer timerWithTimeInterval:2.0 target:self selector:@selector(run) userInfo:nil repeats:YES];
//定时器添加到UITrackingRunLoopMode模式，一旦runloop切换模式，那么定时器就不工作
// [[NSRunLoop currentRunLoop] addTimer:timer forMode:UITrackingRunLoopMode];
//定时器添加到NSDefaultRunLoopMode模式，一旦runloop切换模式，那么定时器就不工作
// [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];
//占位模式：common modes标记
//被标记为common modes的模式 kCFRunLoopDefaultMode UITrackingRunLoopMode
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
// NSLog(@"%@",[NSRunLoop currentRunLoop]);
}
- (void)run
{
NSLog(@"---run---%@",[NSRunLoop currentRunLoop].currentMode);
}
DispatchSourceTimer¶
let queue = DispatchQueue(label: "com.example.timer")
let timer = DispatchSource.makeTimerSource(queue: queue)
timer.schedule(deadline: .now(), repeating: 1.0)
timer.setEventHandler {
print("Timer fired!")
// 你的代码...
}
// 启动定时器
timer.resume()
// 当完成时，取消定时器，释放资源。
timer.cancel()