mikeash

+ (id)sharedWhatever
{
	static Whatever *whatever = nil;
	if( !whatever )
	{
		Whatever *newWhatever = [[self alloc] init];
		if( !OSAtomicCompareAndSwapPtrBarrier( nil, newWhatever, (void *)&whatever ) )
		{
			[newWhatever release];
		}

mikeash

+ (id)sharedInstance {
    id singleton = objc_getAssociatedObject(...);
    if(!singleton) {
        [lock lock];
        singleton = objc_getAssociatedObject(...);
        if(!singleton)
            objc_setAssociatedObject([[self alloc] init], ...);
        [lock unlock];
    }
}

mikeash

#define BIT_SET(array, bit) (array[bit / 8] |= (1 << (bit % 8)))
#define BIT_CLEAR(array, bit) (array[bit / 8] &= ~(1 << (bit % 8)))
#define BIT_GET(array, bit) ((array[bit / 8] | (1 << (bit % 8))) != 0)

uint8_t array[5];
bzero(array, sizeof(array);
BIT_SET(array, 18);
BIT_GET(array, 18);

mikeash

#import <Foundation/Foundation.h>
#import <pthread.h>

typedef void (^MyBlock)(void);
typedef void (*MyFunc)(void *);

static void Block(MyBlock block)
{
    NSLog(@"Block called with %p", block);
}

mikeash

- (id)fooWithError: (NSError **)outError
{
    id obj = [self barWithThing: @"thing" error: outError];
    if(!obj)
        obj = [self quuxWithThing: @"thing" error: outError];
    return obj;
}

mikeash

// NSURLConnection wrapper
// like NSURLConnection, requires a runloop, callbacks happen in runloop that set up load
@interface LDURLLoader : NSObject
{
    NSURLConnection *_connection;
    NSTimeInterval _timeout;
    NSTimer *_timeoutTimer;
    NSURLResponse *_response;
    long long _responseLengthEstimate;
    NSMutableData *_accumulatedData;

mikeash

#import <Foundation/Foundation.h>


// .h file
struct MyConstantsStruct
{
    NSString *foo;
    NSString *bar;

mikeash

@interface NSFileReference : NSObject {
    // internal storage would probably be NSURL, but could be
    // NSString holding a path, FSRef, alias data, whatever
}

- (id)initWithPath: (NSString *)path;
- (id)initWithFileSystemRepresentation: (const char *)path;
- (id)initWithFSRef: (FSRef *)ref;
- (id)initWithAliasData: (NSData *)data;
- (id)initWithURL: (NSURL *)url;

mikeash

dispatch_block_t RecursiveBlock(void (^block)(dispatch_block_t recurse))
{
    // assuming ARC, so no explicit copy
    return ^{ block(RecursiveBlock(block)); };
}

typedef void (^OneParameterBlock)(id parameter);

OneParameterBlock RecursiveBlock1(void (^block)(OneParameterBlock recurse, id parameter))
{

mikeash

// function
void with(id obj, void (^block)(id obj))
{
    block(obj);
}

// example use
with(blah, ^(Blah *blah) {
    // use blah here
});