iOS 从 RSS Feed 获取日期字符串

Question

我有一个 XML 解析器，它使用 RaptureXML 获取每个项目并将其显示在表格单元格中。我已经可以获取标题和描述，但我似乎不知道如何获取日期。

这是我到目前为止的日期:

NSString* dateString;

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"EEEE MMMM d, YYYY"];
dateString = [formatter stringFromDate:self.pubDate];


[articleAbstract appendAttributedString:
 [[NSAttributedString alloc] initWithString: dateString]
 ];

我一直在调试器中显示这个:

'NSInvalidArgumentException', reason: 'NSConcreteAttributedString initWithString:: nil value'

我不知道我做错了什么。这是完整的代码:

RSSItem.h

#import <Foundation/Foundation.h>

@interface RSSItem : NSObject

@property (strong, nonatomic) NSString* title;
@property (strong, nonatomic) NSString* description;
@property (strong, nonatomic) NSURL* link;
@property (strong, nonatomic) NSAttributedString* cellMessage;
@property (strong, nonatomic) NSDate* pubDate;
@property (strong, nonatomic) NSString* dateString;

@end

RSSItem.m

#import "RSSItem.h"
#import "GTMNSString+HTML.h"

@implementation RSSItem

-(NSAttributedString*)cellMessage

{ 如果 (_cellMessage!=nil) 返回 _cellMessage;

NSDictionary* boldStyle = @{NSFontAttributeName: [UIFont fontWithName:@"Helvetica-Bold" size:16.0]};
NSDictionary* normalStyle = @{NSFontAttributeName: [UIFont fontWithName:@"Helvetica" size:16.0]};

NSMutableAttributedString* articleAbstract = [[NSMutableAttributedString alloc] initWithString:self.title];

[articleAbstract setAttributes:boldStyle
                         range:NSMakeRange(0, self.title.length)];


[articleAbstract appendAttributedString:
 [[NSAttributedString alloc] initWithString:@"\n\n"]
 ];

// Parse for date

NSString* dateString;

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"EEEE MMMM d, YYYY"];
dateString = [formatter stringFromDate:self.pubDate];


[articleAbstract appendAttributedString:
 [[NSAttributedString alloc] initWithString: dateString]
 ];

[articleAbstract appendAttributedString:
 [[NSAttributedString alloc] initWithString:@"\n\n"]
 ];

int startIndex = [articleAbstract length];

NSString* description = [NSString stringWithFormat:@"%@...", [self.description substringToIndex:100]];
description = [description gtm_stringByUnescapingFromHTML];

[articleAbstract appendAttributedString:
 [[NSAttributedString alloc] initWithString: description]
 ];

[articleAbstract setAttributes:normalStyle
                         range:NSMakeRange(startIndex, articleAbstract.length - startIndex)];

_cellMessage = articleAbstract;
return _cellMessage;

}

@end

编辑:这是我的 RSS 加载器

#import "RSSItem.h"

#define kBgQueue dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)

@implementation RSSLoader

-(void)fetchRssWithURL:(NSURL*)url complete:(RSSLoaderCompleteBlock)c
{
dispatch_async(kBgQueue, ^{

    //work in the background
    RXMLElement *rss = [RXMLElement elementFromURL: url];
    RXMLElement* title = [[rss child:@"channel"] child:@"title"];        
    RXMLElement* pubDate = [[rss child:@"channel"] child:@"pubDate"];

    NSString *usableDate = [pubDate];       

    NSArray* items = [[rss child:@"channel"] children:@"item"];

    NSMutableArray* result = [NSMutableArray arrayWithCapacity:items.count];

    //more code
    for (RXMLElement *e in items) {

        //iterate over the articles
        RSSItem* item = [[RSSItem alloc] init];
        item.title = [[e child:@"title"] text];            
        item.pubDate = usableDate
        item.description = [[e child:@"description"] text];
        item.link = [NSURL URLWithString: [[e child:@"link"] text]];
        [result addObject: item];
    }

    c([title text], result);
});

}

有人可以帮我正确解析我的日期吗？

Answer 1

看起来 stringFromDate 返回 nil。

如果您的意思是 YYYY 是年份，那是不正确的，您应该改用 yyyy。但我不认为日期格式有问题。也许 pubDate 为零？