Question

我试图将NSString转换为NSDate

NSString destructString是2015-01-04 08:36:42 +0000

我知道问题始于我在下面评论过的地方，但我似乎无法找到问题所在。

程序在此时停止并在标题中给出错误。

代码的要点是比较两个日期以查看哪个日期较旧。

PFQuery *query = [PFQuery queryWithClassName:self.parseClassName];


NSDate *today = [[NSDate alloc]init];



[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
    if(!error){
    for(PFObject* object in [self objects]){
        NSLog(@"OBJECT:  %@", object);
        PAWPost *post = [[PAWPost alloc] initWithPFObject:object];
        NSLog(@"post: %@", post);
        NSLog(@"today: %@", today);

        NSString *destructString = [post.object objectForKey:selfDestructDateKey];
            NSLog(@"destruct string: %@", destructString);

        NSDateFormatter *dateFormat = [[NSDateFormatter alloc]init];

        [dateFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss zz"];

        //SOURCE OF PROBLEM BEGINS HERE
        NSDate *destructDate = [dateFormat dateFromString:destructString];

        NSLog(@"destruct date: %@", destructDate);

        if([destructDate compare:today] == NSOrderedDescending){
            [object deleteEventually];
            NSLog(@"DESCENDING");
        }

        else
            NSLog(@"NOT DESCENDING");

    }

    }else {

        NSLog(@"Error in findObjectsInBackgroundWithBlock for destruct purposes");
    }
}];

我也知道有关于此主题的另一篇文章，但我已经尝试过修复（重做格式化），但它没有解决问题。提前致谢！

Answer 1

如果对象的类型可能不同，您应该添加类型检查，因为我添加到您的代码

[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
    if(!error){
    for(PFObject* object in [self objects]){
        NSLog(@"OBJECT:  %@", object);
        PAWPost *post = [[PAWPost alloc] initWithPFObject:object];
        NSLog(@"post: %@", post);
        NSLog(@"today: %@", today);

        id destructString = [post.object objectForKey:selfDestructDateKey];
            NSLog(@"destruct string: %@", destructString);
     if ([destructString isKindOfClass:[NSDate class]]) { // already date 
           NSDate * destructDate = (NSDate *)destructString;
     } else { // parse string  
        NSDateFormatter *dateFormat = [[NSDateFormatter alloc]init];

        [dateFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss zz"];

        //SOURCE OF PROBLEM BEGINS HERE
        NSDate *destructDate = [dateFormat dateFromString:destructString];

        NSLog(@"destruct date: %@", destructDate);

        if([destructDate compare:today] == NSOrderedDescending){
            [object deleteEventually];
            NSLog(@"DESCENDING");
        }

        else
            NSLog(@"NOT DESCENDING");
}
    }

    }else {

        NSLog(@"Error in findObjectsInBackgroundWithBlock for destruct purposes");
    }
}];

_NSDate长度无法识别的选择器发送到实例

1 个答案: