iOS从RSS Feed获取日期字符串 [英] iOS getting date string from RSS Feed

问题描述

我有一个XML解析器，它使用RaptureXML来抓取每个项目并在表格单元格中显示它。我已经可以获得标题和描述，但我似乎无法弄清楚如何获取日期。

这是迄今为止我所拥有的日期：

  NSString * dateString; 
 
 NSDateFormatter * formatter = [[NSDateFormatter alloc] init]; 
 [格式化程序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：

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

我不知道我做错了什么。以下是完整代码：

RSSItem.h

  #import< Foundation / Foundation.h> 
 
 @interface RSSItem：NSObject 
 
 @property（强，非原子）NSString * title; 
 @property（强，非原子）NSString * description; 
 @property（强，非原子）NSURL *链接; 
 @property（强，非原子）NSAttributedString * cellMessage; 
 @property（强，非原子）NSDate * pubDate; 
 @property（强，非原子）NSString * dateString; 
 
 @end 
  

RSSItem.m

  #importRSSItem.h
 #importGTMNSString + HTML.h
 
 @implementation RSSItem 
 
  - （NSAttributedString *）cellMessage 
  

{
if（_cellMessage！= nil）return _cellMessage;

  NSDictionary * boldStyle = @ {NSFontAttributeName：[UIFont fontWithName：@ Helvetica-Bold尺寸：16.0]}; 
 NSDictionary * normalStyle = @ {NSFontAttributeName：[UIFont fontWithName：@Helveticasize：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] 
]; 
 
 //解析日期
 
 NSString * dateString; 
 
 NSDateFormatter * formatter = [[NSDateFormatter alloc] init]; 
 [格式化程序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 Loader

  #importRSSItem.h
 
 #define kBgQueue dispatch_get_global_queue（DISPATCH_QUEUE_PRIORITY_DEFAULT，0）
 
 @implementation RSSLoader 
 
  - （void）fetchRssWithURL：（NSURL *）url complete：（RSSLoaderCompleteBlock）c 
 {
 dispatch_async（kBgQueue，^ {
 
 //在后台工作
 RXMLElement * rss = [RXMLElement elementFromURL：url]; 
 RXMLElement * title = [[ rss child：@channel] child：@title]; 
 RXMLElement * pubDate = [[rss child：@channel] child：@pubDate]; 
 
 NSString * usefulDate = [pubDate]; 
 
 NSArray * items = [[rss child：@channel] children：@item]; 
 
 NSMutableArray * result = [NSMutableArray arrayWithCapacity：items.count]; 
 
 //更多代码
 for（RXMLElement * e in items）{
 
 //迭代文章
 RSSItem * item = [[RSSItem alloc] init]; 
 item.title = [[e child：@title] text]; 
 item.pubDate = usefulDate 
 item.description = [[e child：@description] text]; 
 item.link = [NSURL URLWithString：[[e child：@link] text]]; 
 [结果addObject：item]; 
} 
 
 c（[标题文本]，结果）; 
}）; 
 
} 
  

有人可以帮我解析我的日期吗？

解决方案

根据您添加到问题中的代码，问题与设置 pubDate的方式有关属性。您将该属性定义为 NSDate ，但您在RSS加载程序代码中为该属性设置了 NSString 值。 / p>

您需要将从XML文件获取的字符串转换为NSDate或从<$ c更改 pubDate 属性$ c> NSDate 到 NSString 。如果您执行后者，则需要更新您之前的代码以反映此更改。

决定实际上取决于您需要对日期执行的操作。

I have an XML parser that uses RaptureXML to grab each item and display it within a table cell. I already can get the title and description, but I can't seem to work out how to get the date.

Here's what I have so far for the 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]
 ];

I keep getting this showing up in the debugger:

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

I don't know what I'm doing wrong. Here's the full code:

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

{ if (_cellMessage!=nil) return _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

EDIT: Here is my RSS Loader

#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);
});

}

Can someone please help me parse my date correctly?

解决方案

Based on the code you added to your question, the problem has to do with how you set the pubDate property. You defined the property to be an NSDate but you set an NSString value to the property in your RSS loader code.

You need to convert the string obtained from the XML file to an NSDate or change your pubDate property from NSDate to NSString. If you do the latter then your earlier code needs to be updated to reflect this change.

The decision is really dependent on what you need to do with the date.

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