前言
本文csdn地址：http://blog.csdn.net/game3108/article/details/51170065
计时器是经常使用的一个组件，比如说登陆操作的时候，点击获取验证码的按钮的时候，需要有一个30秒的倒计时，防止用户误点或者多次点击。
因此写了个时间控制的组件，用来控制倒计时等操作，具体代码放在了github上，
正文
在iOS里，定时操作主要有两个办法
NSTimer的
scheduledTimerWithTimeInterval方法，设置时间间隔，执行相应的函数。
使用NSTimer的话，要注意在该线程上是否有runloop，以及添加的Runloop Mode，不然容易出现滑动scrollview的时候，倒计时卡住的情况。GCD的dispatch source。使用
dispatch_source_set_timer来设置定时器。
void
dispatch_source_set_timer(dispatch_source_t source,
dispatch_time_t start,
uint64_t interval,
uint64_t leeway);
方法的四个参数，分别是：
- source：事件源
- start: 开始时间
- interval:间隔时间
- leeway:精度
配合上
void
dispatch_source_set_event_handler(dispatch_source_t source,
dispatch_block_t handler);
设置事件源的block回调，就可以完成定时器的设置。
代码讲解
TimerTicker 时间操作类
//
// TimerTicker.h
// TimerTickerManager
//
// Created by game3108 on 16/4/15.
// Copyright © 2016年 game3108. All rights reserved.
//
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
typedef NS_ENUM(NSInteger , TimerTickerType){
TypeStop = 0,
TypeOnFire = 1,
TypePause =2,
TypeNone = 3
};
@protocol TimerTickerDelegate <NSObject>
- (void) onTimerStop;
- (void) onTimerTicker:(CGFloat) ticker;
@end
@interface TimerTicker : NSObject
@property (nonatomic, assign) CGFloat endNumber;
@property (nonatomic, assign) CGFloat startNumber;
@property (nonatomic, assign) CGFloat tickerGap;
@property (nonatomic, assign) BOOL needStop;
@property (nonatomic, weak) id<TimerTickerDelegate> delegate;
- (dispatch_source_t)startTimeTicker;
- (void)stopTimerTicker;
- (void)pauseTimerTicker;
- (void)resumeTimerTicker;
- (TimerTickerType)getTimerTickerType;
@end
//
// TimerTicker.m
// TimerTickerManager
//
// Created by game3108 on 16/4/15.
// Copyright © 2016年 game3108. All rights reserved.
//
#import "TimerTicker.h"
@interface TimerTicker(){
dispatch_source_t _timer;
BOOL _onFire;
}
@end
@implementation TimerTicker
- (instancetype)init{
self = [super init];
if ( self ){
_tickerGap = 1;
_startNumber = 0;
_endNumber = 0;
_needStop = NO;
}
return self;
}
#pragma mark TimerTicker function
- (dispatch_source_t)startTimeTicker{
if ( _timer ){
if ( !_onFire )
dispatch_resume(_timer);
dispatch_source_cancel(_timer);
_timer = nil;
}
CGFloat endNumber = _endNumber;
CGFloat startNumber = _startNumber;
BOOL needStop = _needStop;
CGFloat tickerGap = _tickerGap;
BOOL timerTickerUp = YES;
if ( _tickerGap < 0 ){
tickerGap = - _tickerGap;
timerTickerUp = NO;
}
if ( (endNumber == startNumber) && needStop ){
[_delegate onTimerStop];
return nil;
}
if ( !_needStop ){
endNumber = startNumber;
}
__block CGFloat timerTicker = (startNumber - endNumber) / tickerGap;
if ( timerTicker > 0 ){
timerTickerUp = NO;
}
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
_timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
dispatch_source_set_timer(_timer, dispatch_walltime(NULL, 0), tickerGap*NSEC_PER_SEC, tickerGap*NSEC_PER_SEC*0.1);
__weak TimerTicker *weakSelf = self;
dispatch_source_set_event_handler(_timer, ^{
BOOL judgeStop = [weakSelf judgeStop:timerTicker andTimeTickerUp:timerTickerUp andNeedStop:needStop];
if(judgeStop) {
[weakSelf onTimerStop];
}else{
[weakSelf onTimertTicker:timerTicker andTickerGap:tickerGap andEndNumber:endNumber];
if ( timerTickerUp )
timerTicker++;
else
timerTicker--;
//NSLog(@"!!!!!!!!!%f",timerTicker);
}
});
dispatch_resume(_timer);
_onFire = YES;
return _timer;
}
- (void)stopTimerTicker{
if ( _timer ){
if ( !_onFire )
dispatch_resume(_timer);
dispatch_source_cancel(_timer);
_timer = nil;
}
}
- (void)pauseTimerTicker{
if ( _timer && _onFire ){
dispatch_suspend(_timer);
_onFire = NO;
}
}
- (void)resumeTimerTicker{
if ( _timer && !_onFire ){
dispatch_resume(_timer);
_onFire = YES;
}
}
- (TimerTickerType)getTimerTickerType{
if ( !_timer )
return TypeStop;
else if ( _onFire )
return TypeOnFire;
else
return TypePause;
}
#pragma mark startTimeTicker related function
- (BOOL) judgeStop:(CGFloat)timerTicker andTimeTickerUp:(BOOL)ifUp andNeedStop:(BOOL)needStop{
BOOL state1 = needStop && ifUp && timerTicker >=0;
BOOL state2 = needStop && !ifUp && timerTicker <= 0;
return state1 || state2;
}
- (void)onTimerStop{
dispatch_source_cancel(_timer);
dispatch_sync(dispatch_get_main_queue(), ^{
[_delegate onTimerStop];
});
}
- (void)onTimertTicker:(CGFloat)timerTicker andTickerGap:(CGFloat)tickerGap andEndNumber:(CGFloat)endNumber{
dispatch_sync(dispatch_get_main_queue(), ^{
[_delegate onTimerTicker:timerTicker*tickerGap+endNumber];
});
}
#pragma mark dealloc
-(void)dealloc{
[self stopTimerTicker];
NSLog(@"timer ticker dealloc");
}
@end
TimerTicker类是直接进行时间控制的操作类。
- startNumber:开始数字
- endNumber:结束数字
- tickerGap:时间间隔精度
- needStop:代表是否停止，设置为YES，则endNumber会无效
- delegate:回调
函数调用包括： - startTimeTicker：开始计时
- stopTimerTicker：结束计时
- pauseTimerTicker： 暂停计时
- resumeTimerTicker：重新计时
- getTimerTickerType: 获取当前类型
startTimeTicker是主要的开始方法。
具体逻辑不是那么复杂，应该可以看得懂，但写的时候碰到很多坑，具体的坑会在后面写出来。
TimerTickerManager控制类
TimerTickerManager主要提供给外部API，简化使用。
//
// TimerTickerManager.h
// TimerTickerManager
//
// Created by game3108 on 16/4/16.
// Copyright © 2016年 game3108. All rights reserved.
//
#import <Foundation/Foundation.h>
#import "TimerTicker.h"
@interface TimerTickerManager : NSObject
+ (instancetype) sharedInstrance;
- (void)startTimerTicker:(id<TimerTickerDelegate>)delegate
withKey:(NSString *)key
withStartNumber:(CGFloat)startNumber
withEndNumber:(CGFloat)endNumber
withTickerGap:(CGFloat)tickerGap;
- (void)startTimerTicker:(id<TimerTickerDelegate>)delegate
withKey:(NSString *)key
withStartNumber:(CGFloat)startNumber
withTickerGap:(CGFloat)tickerGap;
- (void)startTimerTicker:(id<TimerTickerDelegate>)delegate
withKey:(NSString *)key
withTickerGap:(CGFloat)tickerGap;
- (void) setTimerTickerDelegate:(id<TimerTickerDelegate>) delegate
withKey:(NSString *)key;
- (void) removeTimerTickerDelegate:(id<TimerTickerDelegate>) delegate
withKey:(NSString *)key;
- (void) removeTimerTickerWithKey:(NSString *)key;
- (void) setTimerTickerStop:(NSString *)key;
- (void) setTimerTickerPause:(NSString *)key;
- (void) setTimerTickerResume:(NSString *)key;
- (BOOL) judgeExistTimerTicker:(NSString *)key;
- (TimerTickerType)getTimerTickerType:(NSString *)key;
@end
//
// TimerTickerManager.m
// TimerTickerManager
//
// Created by game3108 on 16/4/16.
// Copyright © 2016年 game3108. All rights reserved.
//
#import "TimerTickerManager.h"
@interface TimerTickerManager(){
NSMutableDictionary *_timerTickerDic;
}
@end
static TimerTickerManager *instrance = nil;
@implementation TimerTickerManager
+ (void)initialize{
instrance = [[TimerTickerManager alloc]init];
instrance->_timerTickerDic = [[NSMutableDictionary alloc]init];
}
+ (instancetype) sharedInstrance{
return instrance;
}
- (void)startTimerTicker:(id<TimerTickerDelegate>)delegate
withKey:(NSString *)key
withStartNumber:(CGFloat)startNumber
withEndNumber:(CGFloat)endNumber
withTickerGap:(CGFloat)tickerGap{
[self startTimerTicker:delegate
withKey:key
withStartNumber:startNumber
withEndNumber:endNumber
withTickerGap:tickerGap
withNeedStop:YES];
}
- (void)startTimerTicker:(id<TimerTickerDelegate>)delegate
withKey:(NSString *)key
withStartNumber:(CGFloat)startNumber
withTickerGap:(CGFloat)tickerGap{
[self startTimerTicker:delegate
withKey:key
withStartNumber:startNumber
withEndNumber:startNumber
withTickerGap:tickerGap
withNeedStop:NO];
}
- (void)startTimerTicker:(id<TimerTickerDelegate>)delegate
withKey:(NSString *)key
withTickerGap:(CGFloat)tickerGap{
[self startTimerTicker:delegate
withKey:key
withStartNumber:0
withEndNumber:0
withTickerGap:tickerGap
withNeedStop:NO];
}
- (void)startTimerTicker:(id<TimerTickerDelegate>)delegate
withKey:(NSString *)key
withStartNumber:(CGFloat)startNumber
withEndNumber:(CGFloat)endNumber
withTickerGap:(CGFloat)tickerGap
withNeedStop:(BOOL)needStop{
TimerTicker *objcTimerTicker = [_timerTickerDic objectForKey:key];
if ( objcTimerTicker ){
objcTimerTicker.tickerGap = tickerGap;
objcTimerTicker.startNumber = startNumber;
objcTimerTicker.endNumber = endNumber;
objcTimerTicker.needStop = needStop;
objcTimerTicker.delegate = delegate;
[objcTimerTicker startTimeTicker];
NSLog(@"timeticker reuse ticker");
}else{
TimerTicker *timerTicker = [[TimerTicker alloc]init];
timerTicker.tickerGap = tickerGap;
timerTicker.startNumber = startNumber;
timerTicker.endNumber = endNumber;
timerTicker.needStop = needStop;
timerTicker.delegate = delegate;
[_timerTickerDic setObject:timerTicker forKey:key];
[timerTicker startTimeTicker];
NSLog(@"timeticker new ticker");
}
}
- (void) setTimerTickerDelegate:(id<TimerTickerDelegate>) delegate
withKey:(NSString *)key{
TimerTicker *objcTimerTicker = [_timerTickerDic objectForKey:key];
if ( objcTimerTicker != nil )
objcTimerTicker.delegate = delegate;
}
- (void) removeTimerTickerDelegate:(id<TimerTickerDelegate>) delegate
withKey:(NSString *)key{
TimerTicker *objcTimerTicker = [_timerTickerDic objectForKey:key];
if ( objcTimerTicker != nil )
objcTimerTicker.delegate = nil;
}
- (void) removeTimerTickerWithKey:(NSString *)key{
[_timerTickerDic removeObjectForKey:key];
}
- (void) setTimerTickerStop:(NSString *)key{
TimerTicker *objcTimerTicker = [_timerTickerDic objectForKey:key];
if ( objcTimerTicker != nil )
[objcTimerTicker stopTimerTicker];
}
- (void) setTimerTickerPause:(NSString *)key{
TimerTicker *objcTimerTicker = [_timerTickerDic objectForKey:key];
if ( objcTimerTicker != nil )
[objcTimerTicker pauseTimerTicker];
}
- (void) setTimerTickerResume:(NSString *)key{
TimerTicker *objcTimerTicker = [_timerTickerDic objectForKey:key];
if ( objcTimerTicker != nil )
[objcTimerTicker resumeTimerTicker];
}
- (BOOL) judgeExistTimerTicker:(NSString *)key{
return [[_timerTickerDic allKeys] containsObject:key];;
}
- (TimerTickerType)getTimerTickerType:(NSString *)key{
TimerTicker *objcTimerTicker = [_timerTickerDic objectForKey:key];
if ( objcTimerTicker != nil )
return [objcTimerTicker getTimerTickerType];
else
return TypeNone;
}
@end
TimerTickerManger使用注意：
1.设置时间方式
默认的startNumber开始时间为0，tickerGap时间间隔为1，使用没有endNumber的调用，就不会停止，tickerGap大于0为增加，小于0为减少。
但如果使用有endNumber的方法，startNumber小于endNumber则一定是倒数，大于则一定是正数，与tickerGap正负无关。
tickerGap为0则没有效果。
如
[[TimerTickerManager sharedInstrance]startTimerTicker:self
withKey:@"key1"
withStartNumber:30
withEndNumber:20
withTickerGap:0.5];
即从30倒计时到20，间隔为0.5，不停触发delegate回调
2.为什么会有setTimerTickerStop还会有removeTimerTickerDelegate方法？
比如注册界面按获取验证码倒计时30秒操作，如果用户触发完30秒倒计时，退出注册界面，这个时候倒计时应该继续进行，如果用户重新打开注册页面，要从上次的倒计时继续进行，所以会有setTimerTickerDelegate,removeTimerTickerDelegate,getTimerTickerType。
一些坑
1.关于循环应用问题
dispatch_source_set_event_handler回调是一个block，所以很容易会出现循环引用问题。
__weak TimerTicker *weakSelf = self;
这个weak也主要为了防止循环引用。但写的一开始的版本还是有循环引用问题，后来检查了才发现，原来是在block内引用了实例变量，比如说
_startNumber等。很多时候也许self.startNumber的形式更容易让人意识到循环引用问题，但用实例变量_startNumber的形式也会有循环引用，block持有self。
2.关于dispatch_suspend与dispatch_resume
首先dispatch_suspend与dispatch_resume在对主线程没有效果。其次，这两个方法对应，拿Apple的注释来说
Calls to dispatch_suspend() must be balanced with calls
to dispatch_resume().
你调用了suspend几次，你想resume的话，就必须要remuse几次，才能继续运行。但remuse的状态下，如果再进行一次resume就会crash，所以要注册一个onFire的状态进行记录，防止多次suspend和resume。
除此以外，在suspend的状态下，如果你设置_timer = nil就会crash，所以必须先resume，再cancel再设为nil，如下：
- (void)stopTimerTicker{
if ( _timer ){
if ( !_onFire )
dispatch_resume(_timer);
dispatch_source_cancel(_timer);
_timer = nil;
}
}
参考资料
1.GCD介绍（三）: Dispatch Sources](http://www.cnblogs.com/zhw511006/archive/2012/04/06/2434714.html)
