bjhomer

//
//  ContentView.swift
//  SwiftUIPlayground
//
//  Created by BJ Homer on 4/26/21.
//

import SwiftUI

jverkoey

static const CGFloat kFontWeightEpsilon = FLT_EPSILON;

@implementation UIFont (CustomizedDynamicType)

+ (nonnull UIFont *)preferredFontWithDefaultSize:(CGFloat)size
                                       textStyle:(nonnull UIFontTextStyle)textStyle {
  return [self preferredFontWithDefaultSize:size
                                  textStyle:textStyle
                                 fontWeight:UIFontWeightRegular
                                     italic:NO];

nicklockwood

extension Data {
  init?(hexString: String) {
    let count = hexString.count / 2
    var data = Data(capacity: count)
    var i = hexString.startIndex
    for _ in 0 ..< count {
      let j = hexString.index(after: i)
      if var byte = UInt8(hexString[i ... j], radix: 16) {
        data.append(&byte, count: 1)
      } else {

keith

Usage

1. swiftc main.swift -emit-module-path main.swiftmodule -emit-executable -enable-private-imports -Xfrontend -enable-implicit-dynamic
2. ./main -> prints From original bar()
3. swiftc -emit-library inject.swift -o inject.dylib -I . -Xlinker -undefined -Xlinker suppress -Xlinker -flat_namespace -Xfrontend -disable-access-control
4. DYLD_INSERT_LIBRARIES=inject.dylib ./main -> prints From replacement bar()

Notes

• Passing -Xfrontend -enable-implicit-dynamic removes you from having to add dynamic to everything you want to be replacable

jankais3r

//Sourced from http://newosxbook.com/ent.jl?ent=&osVer=iOS13
abs-client
absinthe-client
adi-client
allow-obliterate-device
allow-softwareupdated
appData
application-identifier
aps-connection-initiate
aps-environment

cellularmitosis

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

        let window = UIWindow(frame: UIScreen.main.bounds)

steipete

static void PSPDFFixiOS12AccessibilityTestCrash(void) {
    let accessibilityLoaderClass = NSClassFromString(@"UIAccessibilityInformationLoader");
    let accessibilitySEL = NSSelectorFromString(@"_loadAccessibilityInformationOnMainThread:");
    __block IMP originalIMP = pspdf_swizzleSelectorWithBlock(accessibilityLoaderClass, accessibilitySEL, ^(id _self, BOOL onMainThread) {
        @try {
            ((void (*)(id, SEL, BOOL))originalIMP)(_self, accessibilitySEL, onMainThread);
        } @catch (NSException *exception) {
            NSLog(@"Exception received: %@", exception);
            if ([exception.name isEqualToString:NSInvalidArgumentException] && [exception.reason containsString:@"_accessibilityLoadAccessibilityInformation"]) {
                NSLog(@"Ignoring IOS 12b5 weirdness...");

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

DougGregor

import Darwin

@dynamicMemberLookup
struct Environment {
  subscript(dynamicMember name: String) -> String? {
    get {
      guard let value = getenv(name) else { return nil }

      return String(validatingUTF8: value)
    }

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