CATransaction Class Reference

Class Methods

animationDuration

Returns the animation duration used by all animations within this transaction group.

+ (CFTimeInterval)animationDuration

Discussion

This is a convenience method that returns an NSNumber containing the seconds for the valueForKey: value returned by the kCATransactionAnimationDuration key.

See Also

• + setAnimationDuration:

Related Sample Code

• LightTable

animationTimingFunction

Returns the timing function used for all animations within this transaction group.

+ (CAMediaTimingFunction *)animationTimingFunction

Discussion

This is a convenience method that returns the CAMediaTimingFunction for the valueForKey: value returned by the kCATransactionAnimationTimingFunction key.

See Also

• + setAnimationTimingFunction:

begin

Begin a new transaction for the current thread.

+ (void)begin

Discussion

The transaction is nested within the thread’s current transaction, if there is one.

See Also

• + commit
• + flush

Related Sample Code

• GeekGameBoard

commit

Commit all changes made during the current transaction.

+ (void)commit

Special Considerations

Raises an exception if no current transaction exists.

See Also

• + begin
• + flush

Related Sample Code

• GeekGameBoard

completionBlock

Returns the completion block object.

+ (void)completionBlock

Discussion

See setCompletionBlock: for a description of the role of the completion block object.

See Also

• + completionBlock

disableActions

Returns whether actions triggered as a result of property changes made within this transaction group are suppressed.

+ (BOOL)disableActions

Discussion

This is a convenience method that returns the boolValue for the valueForKey: value returned by the kCATransactionDisableActions key.

See Also

• + setDisableActions:

Related Sample Code

• LightTable

flush

Flushes any extant implicit transaction.

+ (void)flush

Discussion

Delays the commit until any nested explicit transactions have completed.

See Also

• + begin
• + commit

Related Sample Code

• GeekGameBoard

lock

Attempts to acquire a recursive spin-lock lock, ensuring that returned layer values are valid until unlocked.

+ (void)lock

Discussion

Core Animation uses a data model that promises not to corrupt the internal data structures when called from multiple threads concurrently, but not that data returned is still valid if the property was valid on another thread. By locking during a transaction you can ensure that data the is read, modified, and set is correctly managed.

See Also

• + unlock

setAnimationDuration:

Sets the animation duration used by all animations within this transaction group.

+ (void)setAnimationDuration:(CFTimeInterval)duration

Parameters

duration

An interval of time used as the duration.

Discussion

This is a convenience method that returns an NSNumber containing the seconds for the valueForKey: value returned by the kCATransactionAnimationDuration key.

See Also

• + animationDuration

setAnimationTimingFunction:

Sets the timing function used for all animations within this transaction group.

+ (void)setAnimationTimingFunction:(CAMediaTimingFunction *)function

Parameters

function

An instance of CAMediaTimingFunction.

Discussion

This is a convenience method that returns the CAMediaTimingFunction for the valueForKey: value returned by the kCATransactionAnimationTimingFunction key.

See Also

• + animationTimingFunction

setCompletionBlock:

Sets the completion block object.

+ (void)setCompletionBlock:(void (^)(void))block

Parameters

block

A block object called when animations for this transaction group are completed.

The block object takes no parameters and returns no value.

Discussion

The completion block object that is guaranteed to be called (on the main thread) as soon as all animations subsequently added by this transaction group have completed (or have been removed.) If no animations are added before the current transaction group is committed (or the completion block is set to a different value,) the block will be invoked immediately.

See Also

• + completionBlock

setDisableActions:

Sets whether actions triggered as a result of property changes made within this transaction group are suppressed.

+ (void)setDisableActions:(BOOL)flag

Parameters

flag

YES, if actions should be disabled.

Discussion

This is a convenience method that invokes setValue:forKey: with an NSNumber containing a YES for the kCATransactionDisableActions key.

See Also

• + disableActions

Related Sample Code

• NineSlice

setValue:forKey:

Sets the arbitrary keyed-data for the specified key.

+ (void)setValue:(id)anObject forKey:(NSString *)key

Parameters

anObject

The value for the key identified by key.

key

The name of one of the receiver's properties.

Discussion

Nested transactions have nested data scope; setting a key always sets it in the innermost scope.

Related Sample Code

• GeekGameBoard
• LightTable

unlock

Relinquishes a previously acquired transaction lock.

+ (void)unlock

See Also

• + lock

valueForKey:

Returns the arbitrary keyed-data specified by the given key.

+ (id)valueForKey:(NSString *)key

Parameters

key

The name of one of the receiver's properties.

Discussion

Nested transactions have nested data scope. Requesting a value for a key first searches the innermost scope, then the enclosing transactions.

NSString * const kCATransactionAnimationDuration;
NSString * const kCATransactionDisableActions;
NSString * const kCATransactionAnimationTimingFunction;
NSString * const kCATransactionCompletionBlock;