前言

NSTimer的特性（坑）上篇文章 提到過官硝，基于這些特性（坑），用GCD寫的定時器似乎更好用？

正文

先看API

NS_ASSUME_NONNULL_BEGIN

typedef NS_ENUM(NSUInteger, JKGCDTimerState) {
    JKGCDTimerStateSuspend = 0,
    JKGCDTimerStateResume,
    JKGCDTimerStateInvalid
};

@interface JKGCDTimer : NSObject

// default is JKGCDTimerStateSuspend
@property (nonatomic, readonly) JKGCDTimerState state;
@property (nonatomic, readonly) NSTimeInterval interval;
@property (nonatomic, strong, readonly) id userInfo;
@property (nonatomic, readonly) BOOL repeats;
@property (nonatomic, copy, readonly) void(^block)(JKGCDTimer *);


// default is mainQueue
+ (instancetype)timerWithTimeInterval:(NSTimeInterval)interval
                             userInfo:(id)userInfo
                              repeats:(BOOL)repeats
                                block:(void (^)(JKGCDTimer *timer))block;

+ (instancetype)timerWithTimeInterval:(NSTimeInterval)interval
                             userInfo:(id)userInfo
                              repeats:(BOOL)repeats
                                queue:(dispatch_queue_t)queue
                                block:(void (^)(JKGCDTimer *timer))block;

// default is mainQueue
+ (instancetype)scheduledTimerWithTimeInterval:(NSTimeInterval)interval
                             userInfo:(id)userInfo
                              repeats:(BOOL)repeats
                                block:(void (^)(JKGCDTimer *timer))block;

+ (instancetype)scheduledTimerWithTimeInterval:(NSTimeInterval)interval
                             userInfo:(id)userInfo
                              repeats:(BOOL)repeats
                                queue:(dispatch_queue_t)queue
                                block:(void (^)(JKGCDTimer *timer))block;


// the following 3 methods are default invoked in the queue
- (void)suspend;
- (void)resume;
- (void)invalidate;

@end

NS_ASSUME_NONNULL_END

接口基本與NSTimer相同喜鼓，簡單說下特性（坑）：
1.timerWithTimeInterval開頭的方法需要手動調(diào)用resume開啟
2.scheduledTimerWithTimeInterval開頭的方法默認(rèn)開啟resume
3.可以通過state屬性獲取當(dāng)前定時器所處狀態(tài)
4.通過userInfo屬性傳遞參數(shù)
5.在不使用時际乘，需要調(diào)用invalidate坡倔，可以直接在vc的dealloc方法中調(diào)用，不存在內(nèi)存泄漏
6.repeats為NO時脖含，可以不手動調(diào)用invalidate方法罪塔，內(nèi)部默認(rèn)調(diào)用
7.repeats為YES時，可以通過suspend和resume對定時器做暫停养葵、恢復(fù)操作
8.可以通過queue設(shè)置定時器工作所在隊(duì)列
9.當(dāng)queue不是主隊(duì)列征堪，suspend resume invalidate這3個方法可以直接調(diào)用，內(nèi)部已經(jīng)切換到指定隊(duì)列关拒，不需要手動切換

這里是源碼

隨手寫的佃蚜，不保證質(zhì)量庸娱，僅供參看，歡迎指正

Have fun谐算！