mayoff

The attached lldb command pblock command lets you peek inside an Objective-C block. It tries to tell you where to find the source code for the block, and the values captured by the block when it was created.

Consider this example program:

#import <Foundation/Foundation.h>

@interface Foo: NSObject
@end

@implementation Foo

tclementdev

libdispatch efficiency tips

The libdispatch is one of the most misused API due to the way it was presented to us when it was introduced and for many years after that, and due to the confusing documentation and API. This page is a compilation of important things to know if you're going to use this library. Many references are available at the end of this document pointing to comments from Apple's very own libdispatch maintainer (Pierre Habouzit).

My take-aways are:

• You should create very few, long-lived, well-defined queues. These queues should be seen as execution contexts in your program (gui, background work, ...) that benefit from executing in parallel. An important thing to note is that if these queues are all active at once, you will get as many threads running. In most apps, you probably do not need to create more than 3 or 4 queues.

• Go serial first, and as you find performance bottle necks, measure why, and if concurrency helps, apply with care, always validating under system pressure. Reuse

mikeash

#!/bin/bash

# Exit the script immediately on error
set -e

# We'll work in /tmp
cd /tmp

# Clone mach_override unless we already have it
if [ ! -d mach_override ]; then

0xced

#!/usr/bin/env bash -e

HOST=${1:-cloudflare.com}
FILENAME=${2:-${HOST%%.*}}

# For file naming, see https://support.ssl.com/Knowledgebase/Article/View/19/0/der-vs-crt-vs-cer-vs-pem-certificates-and-how-to-convert-them
# For HTTP Public Key Pinning (HPKP), see https://developer.mozilla.org/en-US/docs/Web/HTTP/Public_Key_Pinning
CERTIFICATE_PEM="${FILENAME}_certificate.ascii.crt"
CERTIFICATE_DER="${FILENAME}_certificate.crt"
PUBKEY_PEM="${FILENAME}_pubkey.ascii.key"

ddunbar

New Build System Tricks

Command Line

alias xcbuild=$(xcode-select -p)/../SharedFrameworks/XCBuild.framework/Versions/A/Support/xcbuild
# THIS DOESNT WORK YET: xcbuild openIDEConsole  # … then switch to Xcode ➡️
xcbuild showSpecs
xcbuild build <foo.pif> [—target <target>]

steipete

# The trick is to link the DeviceSupport folder from the beta to the stable version.
# sudo needed if you run the Mac App Store version. Always download the dmg instead... you'll thank me later :)

# Support iOS 15 devices (Xcode 13.0) with Xcode 12.5:
sudo ln -s /Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/15.0 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport

# Then restart Xcode and reconnect your devices. You will need to do that for every beta of future iOS versions

# (A similar approach works for older versions too, just change the version number after DeviceSupport)

syncs.d

#!/usr/sbin/dtrace -q -s
/*
Overly spammy, mostly covered by the other probes (every "read" or "write" is a "request")
CFPreferencesServer$target:::request {
printf("REQUEST from pid %d at %Y ( domain: %s, user: %s, host: %s, container: %s, managed: %d)\n", arg0, walltimestamp, copyinstr(arg1) != NULL ? copyinstr(arg1) : "(NULL)" ?: "(NULL)", copyinstr(arg2) != NULL ? copyinstr(arg2) : "(NULL)", copyinstr(arg3) != NULL ? copyinstr(arg3) : "(NULL)", copyinstr(arg4) != NULL ? copyinstr(arg4) : "(NULL)", arg5);
}
*/

CFPreferencesServer$target:::write_rejected {
printf("REJECTED WRITE OF KEY %s request from pid %d for reason %s at %Y ( domain: %s, user: %s, host: %s, container: %s)\n", copyinstr(arg1) != NULL ? copyinstr(arg1) : "(NULL)", arg0, copyinstr(arg6) != NULL ? copyinstr(arg6) : "(NULL)", walltimestamp, copyinstr(arg2) != NULL ? copyinstr(arg2) : "(NULL)", copyinstr(arg3) != NULL ? copyinstr(arg3) : "(NULL)", copyinstr(arg4) != NULL ? copyinstr(arg4) : "(NULL)", copyinstr(arg5) != NULL ? copyinstr(arg5)

steipete

@interface PSPDFWindow ()
@property (nonatomic, strong) UIViewController *realRootViewController;
@end

@implementation PSPDFWindow

- (void)setHidden:(BOOL)hidden {
    [super setHidden:hidden];

    // Workaround for rdar://19592583