CkoRss Objective-C Reference Documentation

CkoRss

Current Version: 9.5.0.75

Represents an RSS document or sub-part of a document such as a channel, image, or item. The RSS API allows one to download, create and modify RSS documents.

Object Creation

CkoRss *obj = [[CkoRss alloc] init];

Properties

DebugLogFilePath
@property (nonatomic, copy) NSString *DebugLogFilePath;

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

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LastErrorHtml
@property (nonatomic, readonly, copy) NSString *LastErrorHtml;

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorText
@property (nonatomic, readonly, copy) NSString *LastErrorText;

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorXml
@property (nonatomic, readonly, copy) NSString *LastErrorXml;

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastMethodSuccess
@property (nonatomic) BOOL LastMethodSuccess;
Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of YES indicates success, a value of NO indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = YES and failure = NO.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to YES. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

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NumChannels
@property (nonatomic, readonly, copy) NSNumber *NumChannels;

The number of channels in the RSS document.

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NumItems
@property (nonatomic, readonly, copy) NSNumber *NumItems;

The number of items in the channel.

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VerboseLogging
@property (nonatomic) BOOL VerboseLogging;

If set to YES, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is NO. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
@property (nonatomic, readonly, copy) NSString *Version;

Version of the component/library, such as "9.5.0.63"

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Methods

AddNewChannel
- (CkoRss *)AddNewChannel;

Adds a new channel to the RSS document. Returns the Rss object representing the Channel which can then be edited.

Returns nil on failure

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AddNewImage
- (CkoRss *)AddNewImage;

Adds a new image to the RSS document. Returns the Rss object representing the image, which can then be edited.

Returns nil on failure

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AddNewItem
- (CkoRss *)AddNewItem;

Adds a new Item to an Rss channel. Returns the Rss object representing the item which can then be edited.

Returns nil on failure

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DownloadRss
- (BOOL)DownloadRss:(NSString *)url;

Downloads an RSS document from the Internet and populates the Rss object with the contents.

Returns YES for success, NO for failure.

More Information and Examples
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DownloadRssAsync (1)
- (CkoTask *)DownloadRssAsync:(NSString *)url;

Creates an asynchronous task to call the DownloadRss method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns nil on failure

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GetAttr
- (NSString *)GetAttr:(NSString *)tag
    attrName:(NSString *)attrName;

Returns the value of a sub-element attribute. For example, to get the value of the "isPermaLink" attribute of the "guid" sub-element, call item.GetAttr("guid","isPermaLink").

Returns nil on failure

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GetChannel
- (CkoRss *)GetChannel:(NSNumber *)index;

Returns the Nth channel of an RSS document. Usually there is only 1 channel per document, so the index argument should be set to 0.

Returns nil on failure

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GetCount
- (NSNumber *)GetCount:(NSString *)tag;

Return the number of sub-elements with a specific tag.

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GetDateStr
- (NSString *)GetDateStr:(NSString *)tag;

The same as GetDate, except the date/time is returned in RFC822 string format.

Returns nil on failure

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GetImage
- (CkoRss *)GetImage;

Return the image associated with the channel.

Returns nil on failure

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GetInt
- (NSNumber *)GetInt:(NSString *)tag;

Return the value of a numeric sub-element as an integer.

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GetItem
- (CkoRss *)GetItem:(NSNumber *)index;

Return the Nth item of a channel as an RSS object.

Returns nil on failure

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GetString
- (NSString *)GetString:(NSString *)tag;

Return the value of an sub-element as a string.

Returns nil on failure

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LoadRssFile
- (BOOL)LoadRssFile:(NSString *)path;

Load an RSS document from a file.

Returns YES for success, NO for failure.

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LoadRssString
- (BOOL)LoadRssString:(NSString *)rssString;

Loads an RSS feed document from an in-memory string.

Returns YES for success, NO for failure.

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MGetAttr
- (NSString *)MGetAttr:(NSString *)tag
    index:(NSNumber *)index
    attrName:(NSString *)attrName;

Get an attribute value for the Nth sub-element having a specific tag. As an example, an RSS item may have several "category" sub-elements. To get the value of the "domain" attribute for the 3rd category, call MGetAttr("category",2,"domain").

Returns nil on failure

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MGetString
- (NSString *)MGetString:(NSString *)tag
    index:(NSNumber *)index;

Get the value of the Nth occurrence of a sub-element. Indexing begins at 0.

Returns nil on failure

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MSetAttr
- (BOOL)MSetAttr:(NSString *)tag
    index:(NSNumber *)index
    attrName:(NSString *)attrName
    value:(NSString *)value;

Set an attribute on the Nth occurrence of a sub-element.

Returns YES for success, NO for failure.

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MSetString
- (BOOL)MSetString:(NSString *)tag
    index:(NSNumber *)index
    value:(NSString *)value;

Set the value of the Nth occurrence of a sub-element. Indexing begins at 0.

Returns YES for success, NO for failure.

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NewRss
- (void)NewRss;

Clears the RSS document.

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Remove
- (void)Remove:(NSString *)tag;

Removes a sub-element from the RSS document.

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SaveLastError
- (BOOL)SaveLastError:(NSString *)path;

Saves the last-error information (the contents of LastErrorXml) to an XML formatted file.

Returns YES for success, NO for failure.

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SetAttr
- (void)SetAttr:(NSString *)tag
    attrName:(NSString *)attrName
    value:(NSString *)value;

Sets the value of a sub-element attribute.

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SetDateNow
- (void)SetDateNow:(NSString *)tag;

Sets the value of a date/time sub-element to the current system date/time.

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SetDateStr
- (void)SetDateStr:(NSString *)tag
    dateTimeStr:(NSString *)dateTimeStr;

The same as SetDate, except the date/time is passed as an RFC822 string.

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SetInt
- (void)SetInt:(NSString *)tag
    value:(NSNumber *)value;

Sets the value of an integer sub-element.

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SetString
- (void)SetString:(NSString *)tag
    value:(NSString *)value;

Sets the value of a sub-element.

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ToXmlString
- (NSString *)ToXmlString;

Returns the RSS document as an XML string.

Returns nil on failure

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Events

To implement an event callback, your application would define and implement a class that inherits from CkoBaseProgress. Your application can implement methods to override some or all of the default/empty method implementations of the CkoBaseProgress base class.

For example:

  CkoRss *rss = [[CkoRss alloc] init];

  MyRssProgress *callbackObj = [[MyRssProgress alloc] init];

  [rss setEventCallbackObject:callbackObj];

MyRssProgress interface example:

#import "CkoRssProgress.h"

@interface MyRssProgress : CkoBaseProgress {

}

    - (id)init;
    - (void)dealloc;
    - (void)dispose;

    - (void)AbortCheck:(BOOL *)abort;

    - (void)BinaryData:(NSData *)data 
        length:(NSNumber *)length;

    - (void)PercentDone:(NSNumber *)pctDone 
        abort:(BOOL *)abort;

    - (void)ProgressInfo:(NSString *)name 
        value:(NSString *)value;

    - (void)TaskCompleted:(CkoTask *)task;

    - (void)TextData:(NSString *)data;

@end
AbortCheck
- (void)AbortCheck:(BOOL *)abort;

Provides the opportunity for a method call to be aborted. The AbortCheck event is fired periodically based on the value of the HeartbeatMs property. If HeartbeatMs is 0, then no AbortCheck events will fire. As an example, to fire 5 AbortCheck events per second, set the HeartbeatMs property equal to 200.

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PercentDone
- (void)PercentDone:(NSNumber *)pctDone
    abort:(BOOL *)abort;

Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This event is only fired when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For operations (Chilkat method calls) that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).

The PercentDone callback counts as an AbortCheck event. For method calls that complete quickly such that PercentDone events fire, it may be that AbortCheck events don't fire because the opportunity to abort is already provided in the PercentDone callback. For time consuming operations, where the amount of time between PercentDone callbacks are long, AbortCheck callbacks may be used to allow for the operation to be aborted in a more responsive manner.

The abort output argument provides a means for aborting the operation. Setting it to YES will cause the method to abort and return a failed status (or whatever return value indicates failure).

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ProgressInfo
- (void)ProgressInfo:(NSString *)name
    value:(NSString *)value;

A general name/value event that provides information about what is happening during a method call. To find out what information is available, write code to handle this event and log the name/value pairs. Most are self-explanatory.

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TaskCompleted
- (void)TaskCompleted:(CkoTask *)task;

Called in the background thread when an asynchronous task completes.

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