CkoZipCrc Objective-C Reference Documentation

CkoZipCrc

Current Version: 9.5.0.75

Calculate a Zip CRC checksum for a file or in-memory data.

Object Creation

CkoZipCrc *obj = [[CkoZipCrc 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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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

BeginStream
- (void)BeginStream;

Provides a way to calculate a CRC by streaming the data a chunk at a time. An application would start by calling BeginStream. Then it would add data by calling MoreData for each additional chunk. After the last chunk has been processed, the EndStream method is called to return the CRC.

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CalculateCrc
- (NSNumber *)CalculateCrc:(NSData *)data;

Calculates a 32-bit CRC for in-memory byte data. This is the 32-bit CRC that would be found in a Zip file header if a file containing the data was added to a zip archive. Returns the CRC32 of the data.

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CrcBd
- (NSNumber *)CrcBd:(CkoBinData *)bd;
Introduced in version 9.5.0.75

Calculates a CRC32 for the bytes contained in bd.

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CrcSb
- (NSNumber *)CrcSb:(CkoStringBuilder *)sb
    charset:(NSString *)charset;
Introduced in version 9.5.0.75

Calculates a CRC32 for the string contained in sb. The charset is the byte representation to be used for the sb when calculating the CRC32. It can be utf-8, utf-16, windows-1252, iso-8859-1, or any of the character encodings (charsets) listed at the link below.

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CrcString
- (NSNumber *)CrcString:(NSString *)str
    charset:(NSString *)charset;
Introduced in version 9.5.0.75

Calculates a CRC32 for a string. The charset is the byte representation to be used for the str when calculating the CRC32. It can be utf-8, utf-16, windows-1252, iso-8859-1, or any of the character encodings (charsets) listed at the link below.

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EndStream
- (NSNumber *)EndStream;

Finalizes and returns the Zip CRC value calculated by calling BeginStream followed by multiple calls to MoreData.

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FileCrc
- (NSNumber *)FileCrc:(NSString *)path;

Calculates the CRC32 of a file. The data contained in the file is streamed for the calculation to keep the memory footprint small and constant. Returns the CRC32 of the file.

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FileCrcAsync (1)
- (CkoTask *)FileCrcAsync:(NSString *)path;

Creates an asynchronous task to call the FileCrc 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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MoreData
- (void)MoreData:(NSData *)data;

Adds additional data to the CRC currently being calculated. (See BeginStream for more information.)

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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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ToHex
- (NSString *)ToHex:(NSNumber *)crc;

Converts a 32-bit integer to a hex 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:

  CkoZipCrc *zipcrc = [[CkoZipCrc alloc] init];

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

  [zipcrc setEventCallbackObject:callbackObj];

MyZipCrcProgress interface example:

#import "CkoZipCrcProgress.h"

@interface MyZipCrcProgress : 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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