ios 中定时器:NSTimer, CADisplayLink, GCD

 #import "ViewController.h"
 #import "RunloopViewController.h"
 @interface ViewController ()

 @property (nonatomic , assign) NSInteger currentIndex;

 @property (nonatomic) CADisplayLink * timerInC;

 @property (nonatomic) UIImageView * imgV;

 @property (nonatomic) NSTimer * timerInN;

 @property (nonatomic) dispatch_source_t timerInG;

 @property (nonatomic , assign) BOOL nsTimerResume;

 @property (nonatomic , assign) BOOL gcdTimerResume;

 @end

 @implementation ViewController

 - (void)viewDidLoad {
     [super viewDidLoad];

     self.view.backgroundColor = [UIColor grayColor];

     self.imgV = [[UIImageView alloc] initWithFrame:CGRectMake(, , , )];
     self.imgV.contentMode = UIViewContentModeScaleAspectFill;
     self.imgV.center = self.view.center;
     [self.view addSubview:self.imgV];

     UIButton * button = [UIButton buttonWithType:(UIButtonTypeSystem)];
     [button setFrame:CGRectMake(, , , )];
     button.center = CGPointMake(self.view.center.x - , self.view.center.y + );
     [self.view addSubview:button];
     [button setTitle:@"CADisplayLink" forState:(UIControlStateNormal)];
     [button setBackgroundColor:[UIColor whiteColor]];
     [button addTarget:self action:@selector(CADisplayLinkAction) forControlEvents:(UIControlEventTouchUpInside)];

     UIButton * button1 = [UIButton buttonWithType:(UIButtonTypeSystem)];
     [button1 setFrame:CGRectMake(, , , )];
     button1.center = CGPointMake(self.view.center.x, self.view.center.y + );
     [self.view addSubview:button1];
     [button1 setTitle:@"NSTimer" forState:(UIControlStateNormal)];
     [button1 setBackgroundColor:[UIColor whiteColor]];
     [button1 addTarget:self action:@selector(NSTimerAction) forControlEvents:(UIControlEventTouchUpInside)];

     UIButton * button2 = [UIButton buttonWithType:(UIButtonTypeSystem)];
     [button2 setFrame:CGRectMake(, , , )];
     button2.center = CGPointMake(self.view.center.x + , self.view.center.y + );
     [self.view addSubview:button2];
     [button2 setTitle:@"GCDTimer" forState:(UIControlStateNormal)];
     [button2 setBackgroundColor:[UIColor whiteColor]];
     [button2 addTarget:self action:@selector(GCDTimerAction) forControlEvents:(UIControlEventTouchUpInside)];

     UIButton * button3 = [UIButton buttonWithType:(UIButtonTypeSystem)];
     [button3 setFrame:CGRectMake(, , , )];
     button3.center = CGPointMake(self.view.center.x, self.view.center.y + );
     [self.view addSubview:button3];
     [button3 setTitle:@"看看Runloop" forState:(UIControlStateNormal)];
     [button3 setBackgroundColor:[UIColor whiteColor]];
     [button3 addTarget:self action:@selector(gotoRunloopAction) forControlEvents:(UIControlEventTouchUpInside)];
 }

 -(void)viewWillAppear:(BOOL)animated
 {
     [self initTimer];
 }

 -(void)initTimer
 {
     ///target selector 模式初始化一个实例
     self.timerInC = [CADisplayLink displayLinkWithTarget:self selector:@selector(changeImg)];
     ///暂停
     self.timerInC.paused = YES;
     ///selector触发间隔
     self.timerInC.frameInterval = ;
     ///加入一个runLoop
     [self.timerInC addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
     self.timerInN = [NSTimer timerWithTimeInterval:0.032 target:self selector:@selector(changeImg) userInfo:nil repeats:YES];
     self.timerInN.fireDate = [NSDate distantFuture];
     self.nsTimerResume = YES;
     [[NSRunLoop currentRunLoop] addTimer:self.timerInN forMode:NSDefaultRunLoopMode];
     self.gcdTimerResume = YES;
 }

 -(void)changeImg
 {
     self.currentIndex ++;
     if (self.currentIndex > ) {
         self.currentIndex = ;
     }
     self.imgV.image = [UIImage imageNamed:[NSString stringWithFormat:@"%ld.jpg",self.currentIndex]];
 }

 -(void)CADisplayLinkAction
 {
     self.nsTimerResume = YES;
     self.timerInN.fireDate = [NSDate distantFuture];
     if (self.timerInG && !self.gcdTimerResume) {
         dispatch_suspend(self.timerInG);
         self.gcdTimerResume = YES;
     }
     self.timerInC.paused = !self.timerInC.paused;
 }

 -(void)NSTimerAction
 {
     self.timerInC.paused = YES;

     if (self.timerInG && !self.gcdTimerResume) {
         dispatch_suspend(self.timerInG);
         self.gcdTimerResume = YES;
     }
     self.timerInN.fireDate = self.nsTimerResume?
         [NSDate distantPast]:[NSDate distantFuture];
     self.nsTimerResume = !self.nsTimerResume;
 }

 -(void)GCDTimerAction
 {
     if (self.gcdTimerResume) {
         self.timerInC.paused = YES;
         self.nsTimerResume = YES;
         self.timerInN.fireDate = [NSDate distantFuture];
         static dispatch_once_t onceToken;
         dispatch_once(&onceToken, ^{
             self.timerInG = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, , , dispatch_get_main_queue());
             dispatch_source_set_timer(self.timerInG,  dispatch_walltime(NULL, * NSEC_PER_SEC), 0.032 * NSEC_PER_SEC, );
             dispatch_source_set_event_handler(self.timerInG, ^{
                 [self changeImg];
             });
         });
         dispatch_resume(self.timerInG);
     }
     else
     {
         dispatch_suspend(self.timerInG);
     }
     self.gcdTimerResume = !self.gcdTimerResume;
 }

 - (void)gotoRunloopAction
 {
     [self.timerInC invalidate];
     self.timerInC = nil;
     [self.timerInN invalidate];
     self.timerInN = nil;
     if (self.timerInG) {
         if (self.gcdTimerResume) {
             dispatch_resume(self.timerInG);
         }
         dispatch_source_cancel(self.timerInG);
         self.timerInG = nil;
     }
     RunloopViewController * vc = [[RunloopViewController alloc] init];
     [self.navigationController pushViewController:vc animated:YES];
 }
 - (void)didReceiveMemoryWarning {
     [super didReceiveMemoryWarning];
     // Dispose of any resources that can be recreated.
 }

 @end