MBMLRuntimeFunctions Class Reference

Inherits from	NSObject
Declared in	MBMLRuntimeFunctions.h

Overview

This class implements a set of MBML functions and supporting methods that provide access to Objective-C runtime information.

These functions are exposed to the Mockingbird environment via <Function ... /> declarations in the MBDataEnvironmentModule.xml file.

For more information on MBML functions, see the MBMLFunction class.

Helper method for looking up classes

`+ resolveClass:error:`

Given a Class or a string containing the name of an Objective-C class, this method returns a Class object.

+ (Class)resolveClass:(id)resolveCls error:(inout MBMLFunctionError **)errPtr

Parameters

`resolveCls`	A `Class` object or an `NSString` instance containing the name of a class.
`errPtr`	If non-`nil` and an error occurs, `*errPtr` will be set to an `MBMLFunctionError` instance indicating the error.

Return Value

A Class object representing the specified class, or nil if the specified class was not recognized by the Objective-C runtime.

Discussion

Note: This method is not exposed to the Mockingbird environment as a an MBML function.

Declared In

MBMLRuntimeFunctions.h

Looking up Classes

`+ classExists:`

Determines whether a given class exists in the Objective-C runtime.

+ (id)classExists:(NSString *)className

Parameters

`className`	The function’s input parameter.

Return Value

If there is a class with the given name, @YES is returned. Otherwise, @NO.

Discussion

This Mockingbird function accepts a single string expression yielding the name of the class.

Expression usage

^classExists(NSString)

The expression above would return YES, because the class NSString is part of the iOS SDK.

Declared In

MBMLRuntimeFunctions.h

`+ getClass:`

Returns the Class object for the given class name.

+ (id)getClass:(NSString *)className

Parameters

`className`	The function’s input parameter.

Return Value

If there is a class with the given name, the corresponding Class object is returned. Otherwise, nil is returned.

Discussion

This Mockingbird function accepts a single string expression yielding the name of the class.

Expression usage

Note: This function is exposed to the Mockingbird environment with a name that differs from that of its implementing method:

^class(NSString)

The expression above would return the Class object representing the NSString class.

Declared In

MBMLRuntimeFunctions.h

Accessing singleton instances

`+ singleton:`

Returns the singleton instance of a given class.

+ (id)singleton:(id)forCls

Parameters

`forCls`	The function’s input parameter.

Return Value

If there is a class with the given name, the corresponding Class object is returned. Otherwise, nil is returned.

Discussion

This Mockingbird function accepts a single object expression yielding either a Class object or an NSString containing the name of an Objective-C class. If the specified class responds to the selector instance, this function returns that instance.

Expression usage

^singleton(MBServiceManager)

The expression above would return the singleton instance of the MBServiceManager class.

Declared In

MBMLRuntimeFunctions.h

Getting a class's hierarchy

`+ inheritanceHierarchyForClass:`

Returns an array containing the inheritance hierarchy of a given class.

+ (id)inheritanceHierarchyForClass:(id)forCls

Parameters

`forCls`	The function’s input parameter.

Return Value

An array containing the Objective-C class hierarchy for the specified class. If no such class was found, nil is returned.

Discussion

This Mockingbird function accepts a single parameter, the class expression, an object expression yielding either a Class object or an NSString containing the name of an Objective-C class.

The first item in the returned array will contain the Class object representing the class identified by class.

Each subsequent item in the array will contain a Class representing the superclass of the item that preceded it.

The last item in the returned array will contain the root class of the hierarchy (which is usually NSObject).

Expression usage

^inheritanceHierarchyForClass(NSMutableString)

The expression above would return an array containing three objects: the Class object for the NSMutableString class, the Class object for NSString, and finally the Class for NSObject.

Declared In

MBMLRuntimeFunctions.h

Checking for method implementations

`+ objectRespondsToSelector:`

Determines whether a given object instance responds to a specific Objective-C message selector.

+ (id)objectRespondsToSelector:(NSArray *)params

Parameters

`params`	The function’s input parameters.

Return Value

If object instance referenced in the object expression responds to the selector specified in the selector expression, the return value will be @YES. Otherwise, @NO will be returned.

Discussion

This Mockingbird function accepts two pipe-separated parameters:

The object, an object expression yielding an NSObject instance, and
The selector, a string expression yielding the selector name.

Expression usage

Note: This function is exposed to the Mockingbird environment with a name that differs from that of its implementing method:

^respondsToSelector($myName|isEqualToString:)

The expression above would evaluate to true if the expression $myName yields an NSString instance (or an instance of any other class that responds to the isEqualToString: message).

Declared In

MBMLRuntimeFunctions.h

`+ classRespondsToSelector:`

Determines whether a given class responds to a specific Objective-C message selector.

+ (id)classRespondsToSelector:(NSArray *)params

Parameters

`params`	The function’s input parameters.

Return Value

If the Objective-C class referenced in the class expression responds to the selector specified in the selector expression, the return value will be @YES. Otherwise, @NO will be returned.

Discussion

This Mockingbird function accepts two pipe-separated parameters:

The class, an object expression yielding either a Class object or an NSString containing the name of an Objective-C class
The selector, a string expression yielding the selector name.

Expression usage

Note: This function is exposed to the Mockingbird environment with a name that differs from that of its implementing method:

^instancesRespondToSelector(NSString|availableStringEncodings)

The expression above evaluates to @YES because the NSString class responds to the availableStringEncodings message.

Declared In

MBMLRuntimeFunctions.h