douglashill

@import Foundation;

#define ENABLE_LOGGING 1

#if ENABLE_LOGGING
#define DHLog(__FORMAT__, ...) NSLog((__FORMAT__), ##__VA_ARGS__)
#else
#define DHLog(...) do { } while (0)
#endif

douglashill

@import Foundation;

@implementation NSArray (DHAccumulate)

- (id)dh_objectByReducingWithOptions:(NSEnumerationOptions)options usingBlock:(id (^)(id object1, id object2))reductionBlock
{
	if (options & NSEnumerationConcurrent) {
		[NSException raise:NSInvalidArgumentException format:@"Bad things will happen if you try to reduce an array concurrently."];
	}
	

douglashill

@implementation NSColor (DHLuminance)

- (CGFloat)dh_luminance
{
	return 0.3 * [self redComponent] + 0.6 * [self greenComponent] + 0.1 * [self blueComponent];
}

@end

// Example usage for an attributed string:

douglashill

@implementation UIScrollView (DHDebugImage)

- (UIImage *)dh_debugImage
{
	CGFloat scaleFactor = 0.1;
	CGAffineTransform const transform = CGAffineTransformMakeScale(scaleFactor, scaleFactor);
	
	CGRect const contentBounds = CGRectApplyAffineTransform((CGRect){.size = [self contentSize]}, transform);

	static CGFloat const cornerRadius = 6;

douglashill

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
	NSString *const stackSymbols = [[NSThread callStackSymbols] componentsJoinedByString:@""];
	NSString *caller;
	for (NSString *possibleCaller in @[@"UIAnimator", @"GestureRecognizer", @"smoothScroll", @"setContentOffset"]) {
		if ([stackSymbols containsString:possibleCaller]) {
			caller = possibleCaller;
			break;
		}
	}

douglashill

@implementation NSFileManager (DHRemoveFile)

- (BOOL)dh_removeItemIfExistsAtURL:(NSURL *)URL error:(NSError **)out_error
{
	NSError *error; // We need this in case out_error is NULL.
	
	if ([self removeItemAtURL:URL error:&error]) {
		return YES;
	}
	

douglashill

// xcrun -sdk macosx clang non-square-problem.c -framework Accelerate  && ./a.out

// Douglas Hill, April 2015
// This demonstrates a problem discussed in Apple bug report 20428946.
// Using LinearAlgebra’s la_solve with a non-square matrix results in an error instead of the expected output.

#import <Accelerate/Accelerate.h>

static void solveUsingLinearAlgebra(float *Adata, float *bdata, int numObservations);
static void solveUsingLAPACK(float *Adata, float *bdata, int numObservations);

douglashill

---
AccessModifierOffset: -2
AlignAfterOpenBracket: true
AlignEscapedNewlinesLeft: false
AlignOperands: true
AlignTrailingComments: true
AllowAllParametersOfDeclarationOnNextLine: true
AllowShortBlocksOnASingleLine: false
AllowShortCaseLabelsOnASingleLine: true
AllowShortFunctionsOnASingleLine: All

douglashill

// It isn’t immediately obvious how to enable secure decoding with NSKeyedUnarchiver.
// NSKeyedUnarchiver has a read-write requiresSecureCoding property, but we normally use:

id decodedObject = [NSKeyedUnarchiver unarchiveObjectWithData:archive];

// so never see an instance to be able to set this property.
// However, it is quite simple. The critical part is that we use the
// normal decodeObject… methods, passing the key of the root object.

NSData *archive;

douglashill

@implementation UINavigationItem (DHDescription)

- (NSString *)description {
	return [self dictionaryWithValuesForKeys:@[@"title", @"titleView", @"prompt", @"hidesBackButton", @"backBarButtonItem", @"leftItemsSupplementBackButton", @"leftBarButtonItems", @"rightBarButtonItems"]].description;
}

@end