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#define DEGREES_RADIANS(angle) ((angle) / 180.0 * M_PI)

- (UIImage*) UIImageCrop:(UIImage *)img withRect:(CGRect)rect {
    CGAffineTransform rectTransform;
    switch (img.imageOrientation)
    {
        case UIImageOrientationLeft:
            rectTransform = CGAffineTransformTranslate(CGAffineTransformMakeRotation(DEGREES_RADIANS(90)), 0, -img.size.height);
            break;
        case UIImageOrientationRight:

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CGRect visibleRect = CGRectMake(0, 0, self.scrollView.contentSize.width, self.scrollView.contentSize.height);
    CGRect centeredRect = CGRectMake(visibleRect.origin.x + visibleRect.size.width/2.0 - self.scrollView.frame.size.width/2.0,
                                     visibleRect.origin.y + visibleRect.size.height/2.0 - self.scrollView.frame.size.height/2.0,
                                     self.scrollView.frame.size.width,
                                     self.scrollView.frame.size.height);
    [self.scrollView scrollRectToVisible:centeredRect animated:NO];

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   NSDate *start = [NSDate date];

   //process

   NSDate *methodFinish = [NSDate date];
   NSTimeInterval executionTime = [methodFinish timeIntervalSinceDate:start];

   NSLog(@"Execution Time: %f", executionTime);

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@interface UIImage (FixOrientation)

- (UIImage *)fixOrientation;

@end

@implementation UIImage (FixOrientation)

- (UIImage *)fixOrientation {
    

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// Method: vImageScaledImage:(UIImage*) sourceImage withSize:(CGSize) destSize
// Returns even better scaling than drawing to a context with kCGInterpolationHigh.
// This employs the vImage routines in Accelerate.framework.
// For more information about vImage, see https://developer.apple.com/library/mac/#documentation/performance/Conceptual/vImage/Introduction/Introduction.html#//apple_ref/doc/uid/TP30001001-CH201-TPXREF101
// Large quantities of memory are manually allocated and (hopefully) freed here.  Test your application for leaks before and after using this method.
+ (UIImage*) vImageScaledImage:(UIImage*) sourceImage withSize:(CGSize) destSize;
{
    UIImage *destImage = nil;
    
    if (sourceImage)

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@implementation CustomOperation

- (instancetype)init {
    self = [super init];
    if (self) {
        
    }
    return self;
}

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- (CGFloat)getTransformScale {
    CGAffineTransform transform = self.transform;
    CGFloat scale = sqrt(transform.a*transform.a + transform.c*transform.c);
    return scale;
}

- (CGFloat)getTransformAngle {
    CGAffineTransform transform = self.transform;
    CGFloat angle = atan2(transform.b, transform.a);
    return angle;

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static void * const MyClassKVOContext = (void*)&MyClassKVOContext;

- (void)addContext {
  [object addObserver:self forKeyPath:NSStringFromSelector(@selector(property)) options:0 context:MyClassKVOContext];
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
  if (context == MyClassKVOContext) {
      if ([keyPath isEqualToString:NSStringFromSelector(@selector(property))]) {

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+ (NSString *)createUniqueId {
    CFUUIDRef cfuuid = CFUUIDCreate(kCFAllocatorDefault);
    CFStringRef string = CFUUIDCreateString(kCFAllocatorDefault, cfuuid);
    CFRelease(cfuuid);
    return CFBridgingRelease(string);
}

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static inline NSString * ImageCacheKeyFromURLRequest(NSURLRequest *request) {
    return [[request URL] absoluteString];
}