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/* Drawing a path in a custom UIView

-(void)drawRect:(CGRect)rect
{
	CGContextRect context = UIGraphicsGetCurrentContext();
	
	CGContextBeginPath(context);
	CGContextMoveToPoint(context, 75, 10);
	CGContextAddLineToPoint(context, 160, 150);
	CGContextAddLineToPoint(context, 10, 150);

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/* 
Using arc4random() to get a floating point value between 0 and a given maximum value. Note that this produces a value that is double the precision of using rand().
*/

-(double)randomValueFromZero:(double)toValue
{
    return double val = floorf(((double)arc4random() / toValue) * 100.0f);
}

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-(void)logAllKeys:(NSDictionary *)userInfo
{
    NSArray *allKeys = [userInfo allKeys];
    for (NSString *key in allKeys) {
        id value = [userInfo valueForKey:key];
        NSString *valueString = @"";
        
        if ([value isKindOfClass:[NSString class]])
            valueString = (NSString *)value;
        else if ([value isKindOfClass:[NSNumber class]])

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#include <sys/socket.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_dl.h>
 
// From http://iphonedevelopertips.com/device/determine-mac-address.html
 
- (NSString *)getMacAddress
{
  int                 mgmtInfoBase[6];

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>

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          From UIView: if (self.window)…    // I'm on screen

From UIViewController: if (self.view.window)…

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CGRect screenBounds = [[UIScreen mainScreen] bounds]; // In points

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-(NSDate *)dateFromString:(NSString *)dateString;

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-(id)initWithSomething:(id)somethingIn
{
    self = [self init];
    self.something = somethingIn;
    return self;
}

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if ([someObject conformsToProtocol:@protocol(NSCopying)]) …