CODEWITHSUNDEEP
iosnsrunloop
Richard
Richard

Reputation: 359

NSRunLoop API difference

NSRunLoop has two apis:

- (BOOL)runMode:(NSString *)mode beforeDate:(NSDate *)limitDate

and

- (void)acceptInputForMode:(NSString *)mode beforeDate:(NSDate *)limitDate

I mean they are same except return value, or there are other differences?

Upvotes: 4

Views: 535

Answers (1)

Rob Napier
Rob Napier

Reputation: 299345

As @DarkDust hints at, it used to have to do with timers. See Chris Kane's discussions on the Cocoa mailing list. At one point, runMode:beforeDate: was a wrapper around limitDateForMode: and acceptInputForMode:beforeDate: (since acceptInputForMode:beforeDate: didn't fire timers). My reading of the docs, headers, and crash stacks suggests that today, they behave identically (calling CFRunLoopRunInMode(), which does fire timers). But I haven't built a test app to confirm.

If you read the original NeXT ObjC manual, acceptInputForMode:beforeDate: used to explicitly not fire timers:

Blocks awaiting input from the ports in the port list for the input mode mode until the time specified by limitDate. Use the limitDateForMode: method to calculate limitDate. If input arrives, it is processed using the NSPort delegates. This method does not check the timers associated with mode, thus it does not fire timers even if their scheduled fire dates have passed.

Timers were explicitly handled as a side effect of limitDateForMode:

Polls mode's input sources for their limit date (if any) and returns the earliest limit date for this mode. Uses the NSPort delegate method limitDateForMode: to determine the limit dates of ports. Fires timers if their limit dates have passed. Polls ports for activities appropriate for mode. Returns nil if there are no input sources for this mode.

Which is why runMode:beforeDate: was added as a convenience (see NSRunloop.h):

@interface NSRunLoop (NSRunLoopConveniences)

- (void)run; 
- (void)runUntilDate:(NSDate *)limitDate;
- (BOOL)runMode:(NSString *)mode beforeDate:(NSDate *)limitDate;

#if (TARGET_OS_MAC && !(TARGET_OS_EMBEDDED || TARGET_OS_IPHONE))
- (void)configureAsServer NS_DEPRECATED(10_0, 10_5, 2_0, 2_0);
#endif

See also from NeXT:

The method limitDateForMode: returns the earliest limit date of all the input sources for the mode NSDefaultRunLoopMode. acceptInputForMode:beforeDate: runs the loop until that date, processing any input it receives until that time. As a convenience, you can use runMode:beforeDate: instead. It invokes acceptInputForMode:beforeDate: and limitDateForMode: with the mode you supply.

So the short answer: history.

Upvotes: 5

Related Questions