废话不多说了，直接给大家贴代码了，具体代码如下所示：

创新互联公司是一家专注于成都网站建设、成都网站制作与策划设计,蓟州网站建设哪家好?创新互联公司做网站,专注于网站建设10多年,网设计领域的专业建站公司;建站业务涵盖:蓟州等地区。蓟州做网站价格咨询:028-86922220

AppDelegate.m

#import "AppDelegate.h"
#import "ViewController.h"
@interface AppDelegate ()
@end
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  // Override point for customization after application launch.
  //当程序在后台停留超过60分的时候，密码会置为空。
  //1小时后将密码重新设置
  [self timeInterval];
  return YES;
}
- (void)applicationWillResignActive:(UIApplication *)application {
  // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
  // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
  //计算时间差
  [self backTime];
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
  //1小时后将密码重新设置
  [self timeInterval];
}
- (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.
}
- (void)applicationWillTerminate:(UIApplication *)application {
  //计算时间差
  [self backTime];
}
#pragma -mark -密码保存1个小时
//计算时间差
- (void)timeInterval
{
  NSLog(@"---timeInterval----");
  //设置一个字符串的时间
  NSString * dateBackString = [[NSUserDefaults standardUserDefaults] objectForKey:@"backGroundTime"];
  NSLog(@"---dateBackString---%@",dateBackString);
  if ([dateBackString isEqual:[NSNull null]] || dateBackString==nil || dateBackString.length ==0) {
  }
  else
  {
    NSInteger time = [self getTimeInterval:dateBackString];
    if (time >= 60) {
      //1小时后将密码清空
      NSUserDefaults *userInfoDefault=[NSUserDefaults standardUserDefaults];
      [userInfoDefault setObject:@"" forKey:@"login-password"];
      [userInfoDefault synchronize];
    }
  }
}
//1小时后将密码重新设置
- (void)backTime
{
  NSLog(@"----backTime-----");
  //计算上报时间差
  NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
  [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
  //结束时间
  NSDate * currentdate = [NSDate date];
  NSString * currentDateString = [dateFormatter stringFromDate: currentdate];
  NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
  [userDefaults setObject:currentDateString forKey:@"backGroundTime"];
  [userDefaults synchronize];
}
//计算时间差
- (NSInteger)getTimeInterval:(NSString *)sendDateString
{
  NSInteger minute;
  if (sendDateString ==nil||sendDateString.length==0) {
  }
  else
  {
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    //结束时间
    NSDate * currentdate = [NSDate date];
    NSDate * currentDate = [dateFormatter dateFromString:[dateFormatter stringFromDate: currentdate]];
    NSDate * endDate = [dateFormatter dateFromString:sendDateString];
    //得到时间差
    NSTimeInterval time = [currentDate timeIntervalSinceDate:endDate];
    //    int days = ((int)time)/(3600*24);
    //    int hours = ((int)time)%(3600*24)/3600;
    //    minute = ((NSInteger)time)%(3600*24)/3600/60;
    minute = (NSInteger)time;
  }
  return minute;
}
@end

另外有需要云服务器可以了解下创新互联建站www.cdcxhl.com，海内外云服务器15元起步，三天无理由+7*72小时售后在线，公司持有idc许可证，提供“云服务器、裸金属服务器、高防服务器、香港服务器、美国服务器、虚拟主机、免备案服务器”等云主机租用服务以及企业上云的综合解决方案，具有“安全稳定、简单易用、服务可用性高、性价比高”等特点与优势，专为企业上云打造定制，能够满足用户丰富、多元化的应用场景需求。

网页标题：iOS密码在进入后台1小时后重新设置-创新互联
标题来源：http://kswjz.com/article/dhhopc.html