现在一些app为了考虑用户信息安全，会加上一些安全设置，多数见于银行类的APP。

APP退到后台时间处理

这个比较简单，只要把退到后台时间存储到本地，打开时再取当前时间，进行比较，需要注意的点是：在程序被杀死时要将时间清空。

- (void)applicationDidEnterBackground:(UIApplication *)application {
    
    application.applicationIconBadgeNumber = 0;
    [[NSUserDefaults standardUserDefaults] setValue:[NSString getNowTimeTimestamp2] forKey:@"EnterBackgroundTime"];
    [[NSUserDefaults standardUserDefaults] synchronize];
    
}
- (void)applicationDidBecomeActive:(UIApplication *)application {
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
    
    NSString *enterBackgroundTime = [[NSUserDefaults standardUserDefaults] valueForKey:@"EnterBackgroundTime"];
   
    if (enterBackgroundTime.length > 5) {
        NSTimeInterval value = [[NSString getNowTimeTimestamp2] floatValue] - [enterBackgroundTime floatValue];
        int minute = (int)value /60%60;
        if (minute >= 30) {
            [self gesturesPasswordView];
        }
    }
}
- (void)applicationWillTerminate:(UIApplication *)application {
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    [[NSNotificationCenter defaultCenter] removeObserver:self name:@"kUserEnterFreeTimeoutNotification" object:nil];
    [[NSUserDefaults standardUserDefaults] setValue:@"" forKey:@"EnterBackgroundTime"];
    [[NSUserDefaults standardUserDefaults] synchronize];
}

APP长时间未操作

这个比较好的方法是给UIApplication建一个分类，在分类里重写sendEvent方法，来对事件进行监听

@interface SJApplication : UIApplication
@property (nonatomic,strong) NSTimer *myTimer;
- (void)resetTimer;
@end

.m

#define kApplicationTimeoutInMinutes 30
#import "SJApplication.h"

@implementation SJApplication

- (void)sendEvent:(UIEvent *)event {
    
    [super sendEvent:event];
    
    if (!_myTimer) {
        
        [self resetTimer];
        
    }
    
    NSSet *allTouches = [event allTouches];

    if ([allTouches count] > 0) {
        
        UITouchPhase phase = ((UITouch *)[allTouches anyObject]).phase;
        
        if (phase == UITouchPhaseBegan || phase == UITouchPhaseEnded) {
            
            [self resetTimer];
            
        }
    }
    
}

//重置时钟
- (void)resetTimer {
  
    if (_myTimer) {
        [_myTimer invalidate];
    }

    int timeout =kApplicationTimeoutInMinutes * 60;//超时时间 分钟，
   
    _myTimer = [NSTimer scheduledTimerWithTimeInterval:timeout target:self selector:@selector(freeTimerNotificate:) userInfo:nil repeats:NO];  
}
//当达到超时时间，发送 kApplicationTimeoutInMinutes通知

- (void)freeTimerNotificate:(NSNotification *)notification {
    
    //在想要获得通知的地方注册这个通知就行了
    
    [[NSNotificationCenter defaultCenter] postNotificationName:@"kUserEnterFreeTimeoutNotification"object:nil];
    
}
@end

AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(gesturesPasswordView) name:@"kUserEnterFreeTimeoutNotification"object:nil];
return YES;
}
- (void)gesturesPasswordView {

}