ROVariant

Overview

This class is designed to read and write a Delphi-compatible variant type. The variant type can be used to represent a piece of data of unknown type and can hold different/changing types of data at runtime.
A number of properties are defined in this class to access the data as regular Objective-C types. The class tries to convert the data in all possible ways but if the data conversion is impossible in the particular case (e.g. a GUID can not be converted to a number) an exception with name ROVariantError will be thrown. The similar exception is thrown in response to attempt to treat the data as an array while a single value is stored.

Location

 

arrayCount

Returns the number of array elements if the ROVariant instance holds the array. An exception will be thrown if the data is not an array.

@property (readonly) int arrayCount

arrayDataType

Returns the array data type code (ROVariantTypeCode enumeration) if the ROVariant instance holds the array. An exception will be thrown if the data is not an array.

@property (readonly) enum ROVariantTypeCode arrayDataType

asBool

Reads or writes the data as boolean.

@property () BOOL asBool

asData  assign

Reads or writes the data as a raw binary data. Will return an internal binary representation of any regular data type if one is stored.

@property (assign) NSData *asData

asDate  assign

Reads or writes the data as date-time value.

@property (assign) NSDate *asDate

asDecimal  assign

Reads or writes the data as fixed-point number value.

@property (assign) NSDecimalNumber *asDecimal

asDouble

Reads or writes the data as floating-point number value.

@property () double asDouble

asGuid  assign

Reads or writes the data as ROGuid value.

@property (assign) ROGuid *asGuid

asInt64

Reads or writes the data as 64 bits integer value.

@property () int64 asInt64

asInteger

Reads or writes the data as integer value.

@property () int asInteger

asString  assign

Reads or writes the data as string value (16 bits per character).

@property (assign) NSString *asString

asUtfString

Reads or writes the data as UTF-8 encoded value (8 bits per character).

@property () char *asUtfString

asVariant  assign

Reads or writes the data as variant value.

@property (assign) ROVariant *asVariant

dataType

Returns the data type code (ROVariantTypeCode enumeration) of the data stored in the ROVariant instance.

@property (readonly) enum ROVariantTypeCode dataType

emptyVariant

Creates a ROVariant instance containing no value.

+ (ROVariant *) emptyVariant

getItemAtIndex:

Allows to read the array element if ROVariant instance holds an array data. An exception will be thrown in the instance holds a single value.

- (ROVariant *) getItemAtIndex:(int)aIndex

Parameters:

  • aIndex: A zero-based index of the element to read.

initWithDataType:value:

Initializes the ROVariant instance and stores the value into it.

- (id) initWithDataType:(enum ROVariantTypeCode)aDataType value:(id<NSCopying>)aValue

Parameters:

  • aDataType: The data type code (see ROVariantTypeCode) of the data to store.
  • aValue: The value to store.

isEmpty

Returns YES if the instance contains no value.

@property (readonly) BOOL isEmpty

isNull

Returns YES if the instance contains NULL value. Note: NULL here is provided for compatibility with Delphi and has nothing to do with C-style NULL representing an empty pointer.

@property (readonly) BOOL isNull

nullVariant

Creates a ROVariant instance containing Delphi-compatible NULL value.

+ (ROVariant *) nullVariant

setArrayLength:type:

Prepares the ROVariant instance to hold an array of specified length and element data type. If the instance already contains an array of the same data type the method will resize the array preserving the content as possible.

- (void) setArrayLength:(int)aLength type:(enum ROVariantTypeCode)aDataType

Parameters:

  • aLength: The length of the array to store.
  • aDataType: The data type code (see ROVariantTypeCode) of the array elements.

setEmpty

Clears any value stored in the ROVariant instance resetting it to empty state.

- (void) setEmpty

setItem:atIndex:

Stores the data into the array element specified by index. The ROVariant instance must be prepared to hold an array with a setArrayLength:type: call.

- (void) setItem:(ROVariant *)aItem atIndex:(int)aIndex

Parameters:

  • aItem: The value to store.
  • aIndex: The index in the array to store the value at.

setNull

Clears any value stored in the ROVariant instance resetting it to Delphi-compatible NULL state.

- (void) setNull

value

Provides read-only access to the internal data storage of the ROVariant instance.

@property (readonly) id<NSObject, NSCopying> value

variantWithBool:

Wrap boolen value into ROVariant instance

+ (ROVariant *) variantWithBool:(BOOL)value

Parameters:

  • value: BOOL value we need to convert to ROVariant

variantWithString:

Wrap NSString value into ROVariant instance

+ (ROVariant *) variantWithString:(NSString *)string

Parameters:

  • string: NSString value we need to convert to ROVariant

 

arrayCount

Returns the number of array elements if the ROVariant instance holds the array. An exception will be thrown if the data is not an array.

@property (readonly) int arrayCount

arrayDataType

Returns the array data type code (ROVariantTypeCode enumeration) if the ROVariant instance holds the array. An exception will be thrown if the data is not an array.

@property (readonly) enum ROVariantTypeCode arrayDataType

asBool

Reads or writes the data as boolean.

@property () BOOL asBool

asData  assign

Reads or writes the data as a raw binary data. Will return an internal binary representation of any regular data type if one is stored.

@property (assign) NSData *asData

asDate  assign

Reads or writes the data as date-time value.

@property (assign) NSDate *asDate

asDecimal  assign

Reads or writes the data as fixed-point number value.

@property (assign) NSDecimalNumber *asDecimal

asDouble

Reads or writes the data as floating-point number value.

@property () double asDouble

asGuid  assign

Reads or writes the data as ROGuid value.

@property (assign) ROGuid *asGuid

asInt64

Reads or writes the data as 64 bits integer value.

@property () int64 asInt64

asInteger

Reads or writes the data as integer value.

@property () int asInteger

asString  assign

Reads or writes the data as string value (16 bits per character).

@property (assign) NSString *asString

asUtfString

Reads or writes the data as UTF-8 encoded value (8 bits per character).

@property () char *asUtfString

asVariant  assign

Reads or writes the data as variant value.

@property (assign) ROVariant *asVariant

dataType

Returns the data type code (ROVariantTypeCode enumeration) of the data stored in the ROVariant instance.

@property (readonly) enum ROVariantTypeCode dataType

isEmpty

Returns YES if the instance contains no value.

@property (readonly) BOOL isEmpty

isNull

Returns YES if the instance contains NULL value. Note: NULL here is provided for compatibility with Delphi and has nothing to do with C-style NULL representing an empty pointer.

@property (readonly) BOOL isNull

value

Provides read-only access to the internal data storage of the ROVariant instance.

@property (readonly) id<NSObject, NSCopying> value

 

emptyVariant

Creates a ROVariant instance containing no value.

+ (ROVariant *) emptyVariant

nullVariant

Creates a ROVariant instance containing Delphi-compatible NULL value.

+ (ROVariant *) nullVariant

variantWithBool:

Wrap boolen value into ROVariant instance

+ (ROVariant *) variantWithBool:(BOOL)value

Parameters:

  • value: BOOL value we need to convert to ROVariant

variantWithString:

Wrap NSString value into ROVariant instance

+ (ROVariant *) variantWithString:(NSString *)string

Parameters:

  • string: NSString value we need to convert to ROVariant

 

getItemAtIndex:

Allows to read the array element if ROVariant instance holds an array data. An exception will be thrown in the instance holds a single value.

- (ROVariant *) getItemAtIndex:(int)aIndex

Parameters:

  • aIndex: A zero-based index of the element to read.

initWithDataType:value:

Initializes the ROVariant instance and stores the value into it.

- (id) initWithDataType:(enum ROVariantTypeCode)aDataType value:(id<NSCopying>)aValue

Parameters:

  • aDataType: The data type code (see ROVariantTypeCode) of the data to store.
  • aValue: The value to store.

setArrayLength:type:

Prepares the ROVariant instance to hold an array of specified length and element data type. If the instance already contains an array of the same data type the method will resize the array preserving the content as possible.

- (void) setArrayLength:(int)aLength type:(enum ROVariantTypeCode)aDataType

Parameters:

  • aLength: The length of the array to store.
  • aDataType: The data type code (see ROVariantTypeCode) of the array elements.

setEmpty

Clears any value stored in the ROVariant instance resetting it to empty state.

- (void) setEmpty

setItem:atIndex:

Stores the data into the array element specified by index. The ROVariant instance must be prepared to hold an array with a setArrayLength:type: call.

- (void) setItem:(ROVariant *)aItem atIndex:(int)aIndex

Parameters:

  • aItem: The value to store.
  • aIndex: The index in the array to store the value at.

setNull

Clears any value stored in the ROVariant instance resetting it to Delphi-compatible NULL state.

- (void) setNull

See Also