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我想获取一个已经构建的 xml，对其进行解析，并首先在 xml 中添加最旧的项目，然后每天再添加 1 个。用来解析的代码是：

- (void)parseRss:(GDataXMLElement *)rootElement entries:(NSMutableArray *)entries {

    NSArray *channels = [rootElement elementsForName:@"channel"];
    for (GDataXMLElement *channel in channels) {            

        NSString *blogTitle = [channel valueForChild:@"title"];                    

        NSArray *items = [channel elementsForName:@"item"];
        for (GDataXMLElement *item in items) {

            NSString *articleTitle = [item valueForChild:@"title"];
            NSString *articleUrl = [item valueForChild:@"guid"];            
            NSString *articleDateString = [item valueForChild:@"pubdate"];        
            NSDate *articleDate = [NSDate dateFromInternetDateTimeString:articleDateString formatHint:DateFormatHintRFC822];
            NSString *articleImage = [item valueForChild:@"description"];
            NSDateFormatter * dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
            [dateFormatter setTimeStyle:NSDateFormatterShortStyle];
            [dateFormatter setDateStyle:NSDateFormatterMediumStyle];

            RSSEntry *entry = [[[RSSEntry alloc] initWithBlogTitle:blogTitle
                                                      articleTitle:articleTitle
                                                        articleUrl:articleUrl
                                                       articleDate:articleDate
                                                      articleImage:articleImage
                                                              date:thedate] autorelease];
            [entries addObject:entry];

        }      
    }

}

我该如何更改它，以便它只会在第一次启动应用程序时添加最旧的项目，等等？

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1 回答 1

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在我输入的 AppDelegate didFinishLaunchingWithOptions 方法中：

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

    if (![defaults integerForKey:@"totalDays"]) {

        // if there is no value for the key, set it to 0
        [defaults setInteger:0 forKey:@"totalDays"];
        [defaults synchronize];
    }
    if (![defaults objectForKey:@"currentDate"]) {
        [defaults setObject:@"32 01" forKey:@"currentDate"];
        //this will ensure that no one's start date ever matches current value
        [defaults synchronize];
    }
    // get the current date
    NSDate *date = [NSDate date];

    // format it
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc]init];
    [dateFormat setDateFormat:@"dd MM"];

    // convert it to a string
    NSString *dateString = [dateFormat stringFromDate:date];

    // free up memory
    [dateFormat release];
    if ([defaults objectForKey:@"currentDate"]){
    NSString *checkdate = [defaults objectForKey:@"currentDate"];
    if (![dateString isEqualToString:checkdate]) {
       //now if your current date is different from the last date it will add 1 to the total days key
        NSInteger currentnumber = [defaults integerForKey:@"totalDays"];
        NSLog(@"The current number is %i", currentnumber);

        [defaults setObject:dateString forKey:@"currentDate"];
        [defaults setInteger:currentnumber+1 forKey:@"totalDays"];
        [defaults synchronize];
        NSLog(@"The new number is %i", [defaults integerForKey:@"totalDays"]);
    }
    }

然后在我添加的 NSPredicate 区域：

NSDate *start = [NSDate dateFromRFC3339String:@"2013-01-01T00:00:00-06:00"];
            NSInteger difference = [[NSUserDefaults standardUserDefaults] integerForKey:@"totalDays"];

NSPredicate *predicate = [NSPredicate predicateWithFormat: @"articleDate < %@",  [NSDate dateWithTimeInterval:(86400*difference) sinceDate:start]];
            NSArray *filteredArray = [entries filteredArrayUsingPredicate: predicate];

最后一点代码有望完成最初的预期。

于 2012-12-18T04:55:18.007 回答