Instance Method

enumerateObjectsAtIndexes:options:usingBlock:

Executes a given block using the objects in the array at the specified indexes.

Declaration

- (void)enumerateObjectsAtIndexes:(NSIndexSet *)s options:(NSEnumerationOptions)opts usingBlock:(void (^)(ObjectType obj, NSUInteger idx, BOOL *stop))block;

Parameters

indexSet

The indexes of the objects over which to enumerate.

opts

A bit mask that specifies the options for the enumeration (whether it should be performed concurrently and whether it should be performed in reverse order).

block

The block to apply to elements in the array.

The block takes three arguments:

obj

The element in the array.

idx

The index of the element in the array.

stop

A reference to a Boolean value. The block can set the value to YES to stop further enumeration of the array. If a block stops further enumeration, that block continues to run until it’s finished. When the NSEnumerationConcurrent enumeration option is specified, enumeration stops after all of the currently running blocks finish. The stop argument is an out-only argument. You should only ever set this Boolean to YES within the block.

Discussion

By default, the enumeration starts with the first object and continues serially through the array to the last element specified by indexSet. You can specify NSEnumerationConcurrent and/or NSEnumerationReverse as enumeration options to modify this behavior.

This method executes synchronously.

See Also

Sending Messages to Elements

- makeObjectsPerformSelector:

Sends to each object in the array the message identified by a given selector, starting with the first object and continuing through the array to the last object.

- makeObjectsPerformSelector:withObject:

Sends the aSelector message to each object in the array, starting with the first object and continuing through the array to the last object.

- enumerateObjectsUsingBlock:

Executes a given block using each object in the array, starting with the first object and continuing through the array to the last object.

- enumerateObjectsWithOptions:usingBlock:

Executes a given block using each object in the array with the specified options.

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