Class: NSValueTransformer
Overview
NSValueTransformer is an abstract class that is used by the Cocoa Bindings technology to transform values from one representation to another.
Class Method Summary (collapse)
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+ allowsReverseTransformation
Returns a Boolean value that indicates whether the receiver can reverse a transformation.
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+ setValueTransformer:forName:
Registers the provided value transformer with a given identifier.
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+ transformedValueClass
Returns the class of the value returned by the receiver for a forward transformation.
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+ valueTransformerForName:
Returns the value transformer identified by a given identifier.
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+ valueTransformerNames
Returns an array of all the registered value transformers.
Instance Method Summary (collapse)
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- reverseTransformedValue:
Returns the result of the reverse transformation of a given value.
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- transformedValue:
Returns the result of transforming a given value.
Methods inherited from NSObject
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Constructor Details
This class inherits a constructor from NSObject
Dynamic Method Handling
This class handles dynamic methods through the method_missing method in the class NSObject
Class Method Details
+ (Boolean) allowsReverseTransformation
Returns a Boolean value that indicates whether the receiver can reverse a transformation. A subclass should override this method to return YES if it supports reverse value transformations.
+ (Object) setValueTransformer(transformer, forName:name)
Registers the provided value transformer with a given identifier.
+ (Class) transformedValueClass
Returns the class of the value returned by the receiver for a forward transformation. A subclass should override this method to return the appropriate class.
+ (NSValueTransformer) valueTransformerForName(name)
Returns the value transformer identified by a given identifier. If valueTransformerForName: does not find a registered transformer instance for name, it will attempt to find a class with the specified name. If a corresponding class is found an instance will be created and initialized using its init: method and then automatically registered with name.
+ (Array) valueTransformerNames
Returns an array of all the registered value transformers.
Instance Method Details
- (Object) reverseTransformedValue(value)
Returns the result of the reverse transformation of a given value. The default implementation raises an exception if allowsReverseTransformation returns NO; otherwise it will invoke transformedValue: with value.A subclass should override this method if they require a reverse transformation that is not the same as simply reapplying the original transform (as would be the case with negation, for example). For example, if a value transformer converts a value in Fahrenheit to Celsius, this method would converts a value from Celsius to Fahrenheit.
- (Object) transformedValue(value)
Returns the result of transforming a given value. A subclass should override this method to transform and return an object based on value.