一、業務場景
1.1、應用掛起后倒計時不停止
1.2、不同業務同號碼倒計時不停止
image
二、解決幾個問題
2.1、基礎數據存儲與管理
記錄對應業務號碼與時間的關系，數據容量小，因此使用NSUserDefaults存儲管理即可：
#pragma mark - NSUserDefaults Data
//獲取當前業務號碼的存儲數據
-(NSDictionary*)queryBusinessInfo
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *key = [self userDefaultsKey];
NSDictionary *countValue = [defaults objectForKey:key];
return countValue;
}
//保存當前業務的最后剩余時間
-(void)saveBusinessInfo:(int)second
{
NSDictionary *countValue = @{@"second":[NSNumber numberWithInt:second],@"saveDate":[NSDate date]};
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *key = [self userDefaultsKey];
[defaults setObject:countValue forKey:key];
[defaults synchronize];
}
//刪除當前業務的存儲數據
-(void)removeBusinessInfo
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *key = [self userDefaultsKey];
[defaults removeObjectForKey:key];
[defaults synchronize];
}
-(NSString*)userDefaultsKey
{
return [NSString stringWithFormat:@"ZWS_%@_%@",_phoneNumber,_business];
}
//清理所有業務存儲數據
+(void)clearData
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSDictionary *dic = [defaults dictionaryRepresentation];
for (id key in dic.allKeys) {
if([key isKindOfClass:[NSString class]]){
if([key hasPrefix:@"ZWS_"]){
[defaults removeObjectForKey:key];
}
}
}
[defaults synchronize];
}
2.2、 程序生命周期監聽
- Application掛起與進入：
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(didEnterBackground) name:UIApplicationDidEnterBackgroundNotification object:nil];
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(didBecomeActive) name:UIApplicationDidBecomeActiveNotification object:nil];
對應接收操作：
-(void)didEnterBackground
{
[self saveBusinessInfo:_currentSecond];
}
-(void)didBecomeActive
{
[self initCountdown];
}
-
UIController退出viewDisappear：
為了盡量減少組件的配置，通過runtime中Method Swizzling(函數混淆)來監聽viewWillDisappear，實現Category:
#pragma mark - hook post notification
@interface UIViewController(lifeCycleSwizHook)
@end
@implementation UIViewController(lifeCycleSwizHook)
+ (void)initialize
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
SEL originalSelector2 = @selector(viewWillDisappear:);
SEL swizzledSelector2 = @selector(zws_swiz_viewWillDisappear:);
[ZWSHookUtils swizzlingInClass:[self class] originalSelector:originalSelector2 swizzledSelector:swizzledSelector2];
});
}
-(void)zws_swiz_viewWillDisappear:(BOOL)animated
{
[[NSNotificationCenter defaultCenter]postNotificationName:@"zws_swiz_viewWillDisappear" object:nil];
[self zws_swiz_viewWillDisappear:animated];
}
對應接收通知：
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(swiz_viewWillDisappear) name:@"zws_swiz_viewWillDisappear" object:nil];
以及接收后操作：
-(void)swiz_viewWillDisappear
{
[self saveBusinessInfo:_currentSecond];
}
-
NSTimer啟動后所持有對象的釋放問題：
Timer控件在啟動后，會添加到NSRunLoop中，因此如果不主動invalidate，action將持續，添加：
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(stopCountdown) name:@"zws_cancelReplayTimer" object:nil];
三、總結
功能實現沒有什么難點，主要是程序邏輯實現問題：NSTimer中消息進程問題與runtimer的簡單使用完善相關配置。ZWSCountdownUtils
