#import "WSTimer.h"

@implementation WSTimer

static NSMutableDictionary *timers;
dispatch_semaphore_t semaphore;

+ (void)initialize {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        timers = [NSMutableDictionary dictionary];
        semaphore = dispatch_semaphore_create(1);
    });
     
}

+ (NSString *)execTask:(void (^)(void))task start:(NSTimeInterval)start interval:(NSTimeInterval)interval repeats:(BOOL)repeats async:(BOOL)async {
    
    // 如果没有任务直接返回
    if (!task || start < 0 || (interval <= 0 && repeats)) return nil;
    // 队列
    dispatch_queue_t queue = async ? dispatch_get_global_queue(0, 0) : dispatch_get_main_queue();
    // 创建定时器
    dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
    // 设置时间
    dispatch_source_set_timer(timer,
                              dispatch_time(DISPATCH_TIME_NOW,start * NSEC_PER_SEC),
                              interval * NSEC_PER_SEC, 0);
    
    // 枷锁
    dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
    // 生成定时器唯一表示
    NSString *name = [NSString stringWithFormat: @"%ld", timers.count];
    // 存放到字典中
    timers[name] = timer;
    // 解锁
    dispatch_semaphore_signal(semaphore);
    // 设置回调
    dispatch_source_set_event_handler(timer, ^{
        task();
        // 不需要重复的任务
        if (!repeats) {
            [self cancelTask: name];
        }
        
    });
    // 启动定时器
    dispatch_resume(timer);
    
    return name;
}

+ (NSString *)execTask:(id)target selector:(SEL)selector start:(NSTimeInterval)start interval:(NSTimeInterval)interval repeats:(BOOL)repeats async:(BOOL)async {
    
    if (!target || !selector) return nil;
    
    return [self execTask:^{
        if ([target respondsToSelector: selector]) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
            [target performSelector: selector];
#pragma clang diagnostic pop

        }
    } start: start interval: interval repeats: repeats async: async];
}

+ (void)cancelTask:(NSString *)name {
    
    if (name.length == 0) return;
    
    // 枷锁
    dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
    
    dispatch_source_t timer = timers[name];
    
    if (timer) {
        dispatch_source_cancel(timer);
        [timers removeObjectForKey: name];
    }
    
    // 解锁
    dispatch_semaphore_signal(semaphore);
}

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface WSTimer : NSObject

/**
 @param task:               任务
 @param start：           开始时间
 @param interval：    每隔多长时间执行
 @param repeates：    是否重复
 @param async：           是否同步执行*/
+ (NSString *)execTask:(void(^)(void))task
           start:(NSTimeInterval)start
        interval:(NSTimeInterval)interval
         repeats:(BOOL)repeats
           async:(BOOL)async;

/**
 @param task:               任务
 @param start：           开始时间
 @param interval：    每隔多长时间执行
 @param repeates：    是否重复
 @param async：           是否同步执行*/
+ (NSString *)execTask:(id)target
              selector:(SEL)selector
                 start:(NSTimeInterval)start
              interval:(NSTimeInterval)interval
               repeats:(BOOL)repeats
                 async:(BOOL)async;

/**
 @param name    定时器唯一标识
 */
+ (void)cancelTask:(NSString *)name;

@end

NS_ASSUME_NONNULL_END

用法

 WeakSelf
 // 创建
self.dataTimer = [WSTimer execTask:^{
  	[weakSelf loadHeadData];
 } start:0 interval:2.0f repeats: YES async: YES];
 // 取消
 [WSTimer cancelTask: self.dataTimer];