CFRunLoopSource is cool. It lets you build behavior similar to the mechanisms that drive setNeedsLayout and setNeedsDisplay in UIKit.
I found myself in need of something like this a couple of times. It's great to know that no matter how many times I say I need to update something, I will get a single callback at the end of the run loop that gives me a chance to perform my work.
Here is a little Swift wrapper that makes the API easier to deal with.
| // | |
| // Signal+Extensions.swift | |
| // Khan Academy | |
| // | |
| // Created by Nacho Soto on 10/1/15. | |
| // Copyright © 2015 Khan Academy. All rights reserved. | |
| // | |
| import ReactiveCocoa |
| #!/usr/bin/perl | |
| # This filter changes all words to Title Caps, and attempts to be clever | |
| # about *un*capitalizing small words like a/an/the in the input. | |
| # | |
| # The list of "small words" which are not capped comes from | |
| # the New York Times Manual of Style, plus 'vs' and 'v'. | |
| # | |
| # 10 May 2008 | |
| # Original version by John Gruber: |
| #!/bin/sh | |
| if [ $# -ne 3 ] ; then | |
| echo "Usage: $0 <ref> <ref> <filename>" | |
| exit 1 | |
| fi | |
| RevA=$1 | |
| RevB=$2 | |
| File=$3 |
| /* | |
| * This is an example provided by Facebook are for non-commercial testing and | |
| * evaluation purposes only. | |
| * | |
| * Facebook reserves all rights not expressly granted. | |
| * | |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS | |
| * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
| * FITNESS FOR A PARTICULAR PURPOSE AND NON INFRINGEMENT. IN NO EVENT SHALL | |
| * FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN |
Interestingly Apple doesn't even use Storyboards in their recently open-sourced ResearchKit as [Peter Steinberger has noticed][1] (under the subheading "Interface Builder").
As expected, Apple keeps improving Storyboards and Xcode. Some of the points that applied to iOS 7 and below don't apply to iOS 8 anymore (and are now marked as such). So while Storyboards inherently still have flaws, I revise my advice from don't use to selectively use where it makes sense.
Even now that iOS 7 is out, I would advise against to use caution when deciding whether to use Storyboards. Here are my reasons:
| var active = false; | |
| function changeRefer(details) { | |
| if (!active) return; | |
| for (var i = 0; i < details.requestHeaders.length; ++i) { | |
| if (details.requestHeaders[i].name === 'Referer') { | |
| details.requestHeaders[i].value = 'http://www.google.com/'; | |
| break; | |
| } |
| // these functions take a swift class's statically referenced method and the instance those methods | |
| // should apply to, and returns a function that weakly captures the instance so that you don't have | |
| // to worry about memory retain cycles if you want to directly use an instance method as a handler | |
| // for some object, like NSNotificationCenter. | |
| // | |
| // For more information, see this post: | |
| // http://www.klundberg.com/blog/capturing-objects-weakly-in-instance-method-references-in-swift/ | |
| func weakify <T: AnyObject, U>(owner: T, f: T->U->()) -> U -> () { | |
| return { [weak owner] obj in |
| NSString *const PSPDFApplicationDidReceiveMemoryWarningNotification = @"PSPDFApplicationDidReceiveMemoryWarningNotification"; | |
| // Test with sudo memory_pressure -l critical. Don't forget to re-set afterwards! | |
| __attribute__((constructor)) static void PSPDFInstallLowMemoryNotificationWarningMac(void) { | |
| static dispatch_source_t source; | |
| static dispatch_once_t onceToken; | |
| dispatch_once(&onceToken, ^{ | |
| source = dispatch_source_create(DISPATCH_SOURCE_TYPE_MEMORYPRESSURE, 0, DISPATCH_MEMORYPRESSURE_WARN|DISPATCH_MEMORYPRESSURE_CRITICAL, dispatch_get_main_queue()); | |
| dispatch_source_set_event_handler(source, ^{ | |
| dispatch_source_memorypressure_flags_t pressureLevel = dispatch_source_get_data(source); |
