simonwhitaker

#import <Foundation/Foundation.h>

void timeThis(NSString *label, NSUInteger iterations, void(^block)()) {
    
    CFAbsoluteTime start = CFAbsoluteTimeGetCurrent();
    for (NSUInteger i = 0; i < iterations; i++) {
        block();
    }
    CFAbsoluteTime interval = CFAbsoluteTimeGetCurrent() - start;
    printf("%s: %lu iterations, %.3fs\n", [label UTF8String], iterations, interval);

simonwhitaker

#!/bin/bash
# 
# git-is-ancestor, by Simon Whitaker
# 
# Suggested usage
# 
# Store this file somewhere, make it executable, then alias
# it to git is-ancestor by putting this in your $HOME/.gitconfig:
# 
# [alias]

simonwhitaker

#import <Foundation/Foundation.h>

typedef NS_OPTIONS(uint32_t, SomeOption) {
    SomeOptionNone = 0,
    SomeOptionFoo = 1 << 0,
    SomeOptionBar = 1 << 1,
};

int main(int argc, char *argv[]) {
    @autoreleasepool {

simonwhitaker

$ cat test.c
#import <stdio.h>
#define NYBBLE 4

int main(int argc, const char * argv[]) {
    unsigned long t = (unsigned long)argc;

    t = (t << NYBBLE) | (t >> (sizeof(t) * 8 - NYBBLE));
    
    printf("t is now 0x%lx\n", t);

simonwhitaker

/*
 * Calling math.h functions like `floor` and `floorf` on CGFloat variables
 * becomes problematic when compiling the same code for both 32-bit and 
 * 64-bit platforms, since CGFloat is double on 64-bit, float on 32-bit. 
 * Hence, if you compile with -Wconversion set, `floorf` will give a warning 
 * on 64-bit, while `floor` gives a warning on 32-bit.
 *
 * Here's a suggested implementation of an architecture-independent `floor` 
 * function, written using plain old function overloading which is enabled 
 * using the `__attribute__((overloadable))` Clang language extension.

simonwhitaker

Here's a nice trick for wrapping a method's implementation in a block, for example for logging the return value.

Have you ever written a method with a load of conditionals and return statements...

- (int)statusCode {
    if (foo) {
        return 1;
    }
    if (bar) {

simonwhitaker

#!/usr/bin/env python
#
# git-flip-flop: checks out two or more commits in a periodic cycle
#
# Save on your $PATH as git-flip-flop
#
# EXAMPLES
#
# Check out abc1234, then def5678, then abc1234, etc, with 
# the default 2s between each checkout

simonwhitaker

/*
Decorate-Sort-Undecorate in Swift

In Swift, you get the length of a String by calling the global function
countElements(). However, The Swift Programming Language states:

> The length of a string cannot be calculated without iterating through 
> the string to consider each of its characters in turn. If you are 
> working with particularly long string values, be aware that the 
> countElements function must iterate over the characters within a string 

simonwhitaker

I was intrigued by this example from The Swift Programming Guide's Extensions section:

extension Double {
    var km: Double { return self * 1_000.0 }
    var m: Double { return self }
    var cm: Double { return self / 100.0 }
    var mm: Double { return self / 1_000.0 }
    var ft: Double { return self / 3.28084 }
}

simonwhitaker

#import <Foundation/Foundation.h>

int main(int argc, char *argv[]) {
    @autoreleasepool {
        NSDateFormatter *goodDateFormatter = [[NSDateFormatter alloc] init];
        goodDateFormatter.dateFormat = @"dd-MM-yyyy HH:mm:ss.SSS";

        NSDateFormatter *badDateFormatter = [[NSDateFormatter alloc] init];
        badDateFormatter.dateFormat = @"dd-MM-YYYY HH:mm:ss.SSS";