1

在没有太多调试线索的情况下，我似乎无法找出导致我的应用程序硬崩溃的代码更改错误。

这是原始方法

+ (NSArray *)currentReservations {
    NSTimeInterval interval = [[NSDate date] timeIntervalSince1970];
    double futureTimeframe = interval + SecondsIn24Hours;
    NSArray *reservations = [Reservation findWithSql:@"select * from Reservation where timestamp < ? and timestamp > ?" withParameters:[NSArray arrayWithObjects:[NSNumber numberWithDouble:ceil(futureTimeframe)], [NSNumber numberWithDouble:floor(interval)], nil]];
    return reservations;
}

该方法设置了一些变量，因此我可以查询数据库以查找具有现在到未来 24 小时之间时间戳的所有记录。我需要更改方法以查询从现在到明天（第二天午夜）之间带有时间戳的所有记录，因此我根据其他 stackoverflow 问题将代码更新为此

+ (NSArray *)currentReservations {
    NSDate *today = [NSDate date];
    NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDateComponents *components = [[NSDateComponents alloc] init];
    [components setDay:1];  // tomorrow
    NSDate *tomorrow = [gregorian dateByAddingComponents:components toDate:today options:0];
//    [components release];  // dont think we need this release, but it is in the example here: https://stackoverflow.com/questions/181459/is-there-a-better-way-to-find-midnight-tomorrow
    NSUInteger unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
    components = [gregorian components:unitFlags fromDate:tomorrow];
    [components setHour:0];
    [components setMinute:0];
    NSDate *tomorrowMidnight = [gregorian dateFromComponents:components];
    [components release], components=nil;
    [gregorian release], gregorian=nil;


    NSTimeInterval interval = [today timeIntervalSince1970];
    NSTimeInterval tomorrowInterval = [tomorrowMidnight timeIntervalSince1970];

    NSArray *reservations = [Reservation findWithSql:@"select * from Reservation where timestamp < ? and timestamp > ?" withParameters:[NSArray arrayWithObjects:[NSNumber numberWithDouble:tomorrowInterval], [NSNumber numberWithDouble:floor(interval)], nil]];
    return reservations;
}

但是，当这两行：

    NSTimeInterval interval = [today timeIntervalSince1970];
    NSTimeInterval tomorrowInterval = [tomorrowMidnight timeIntervalSince1970];

包括应用程序崩溃。我通过将它们注释掉等将其缩小到这两行。

我完全不知道出了什么问题。

4

2 回答 2

1

由于您的崩溃堆栈跟踪位于 _CFAutoreleasePoolPop 内的 objc_msgSend 中，因此您可以推断它可能是一个过度释放的错误。

这一行是错误的：

[components release], components=nil;

您不拥有那里的组件。查看提供给您的方法的名称。你过度释放它。

于 2011-11-02T16:44:10.377 回答
0

正如 rob mayoff 所说，第二个版本是错误的（而第一个版本是必要的）。试试这个：

+ (NSArray *)currentReservations {
    NSDate *today = [NSDate date];
    NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDateComponents *components = [[[NSDateComponents alloc] init] autorelease];
    [components setDay:1];  // tomorrow
    NSDate *tomorrow = [gregorian dateByAddingComponents:components toDate:today options:0];
    NSUInteger unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
    components = [gregorian components:unitFlags fromDate:tomorrow];
    [components setHour:0];
    [components setMinute:0];
    NSDate *tomorrowMidnight = [gregorian dateFromComponents:components];
    [gregorian release], gregorian=nil;


    NSTimeInterval interval = [today timeIntervalSince1970];
    NSTimeInterval tomorrowInterval = [tomorrowMidnight timeIntervalSince1970];

    NSArray *reservations = [Reservation findWithSql:@"select * from Reservation where timestamp < ? and timestamp > ?" withParameters:[NSArray arrayWithObjects:[NSNumber numberWithDouble:tomorrowInterval], [NSNumber numberWithDouble:floor(interval)], nil]];
    return reservations;
}
于 2011-11-02T16:52:05.923 回答