get circular part of image - ios

Question

i am trying to imitate the new contact ios7 behavior.
I have a UIScrollView with a UImageView inside.
With this code i can draw the circular shape in front of the image.
-(void)viewWillAppear:(BOOL)animated
{
CGFloat screenHeight = [[UIScreen mainScreen] bounds].size.height;
int position = 0;
if (screenHeight == 568)
{
position = 124;
}
else
{
position = 80;
}
CAShapeLayer *circleLayer = [CAShapeLayer layer];
UIBezierPath *path2 = [UIBezierPath bezierPathWithOvalInRect:
CGRectMake(0.0f, position, 320.0f, 320.0f)];
[path2 setUsesEvenOddFillRule:YES];
[circleLayer setPath:[path2 CGPath]];
[circleLayer setFillColor:[[UIColor clearColor] CGColor]];
path;
path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, 320, screenHeight-44) cornerRadius:0];
[path appendPath:path2];
[path setUsesEvenOddFillRule:YES];
fillLayer = [CAShapeLayer layer];
fillLayer.path = path.CGPath;
fillLayer.fillRule = kCAFillRuleEvenOdd;
fillLayer.fillColor = [UIColor blackColor].CGColor;
fillLayer.opacity = 0.8;
[self.view.layer addSublayer:fillLayer];
UILabel *moveLabel = [[UILabel alloc]initWithFrame:CGRectMake(0, 10, 320, 50)];
[moveLabel setText:#"Mueva y escale"];
[moveLabel setTextAlignment:NSTextAlignmentCenter];
[moveLabel setTextColor:[UIColor whiteColor]];
[self.view addSubview:moveLabel];
}
I need to get the portion of the image that is inside the circle when the user choose "Use Photo" option.

Answer 1

I wrote this category
#implementation UIImage (PathCropping)
-(UIImage *)imageCroppedWithPath:(UIBezierPath *)path
{
return [self imageCroppedWithPath:path invertPath:NO];
}
-(UIImage *)imageCroppedWithPath:(UIBezierPath *)path
invertPath:(BOOL)invertPath
{
float scaleFactor = [self scale];
CGRect imageRect = CGRectMake(0, 0, self.size.width * scaleFactor, self.size.height *scaleFactor);
CGColorSpaceRef colorSpace = CGImageGetColorSpace(self.CGImage);
CGContextRef context = CGBitmapContextCreate(NULL,
imageRect.size.width,
imageRect.size.height ,
CGImageGetBitsPerComponent(self.CGImage),
0,
colorSpace,
(CGBitmapInfo)CGImageGetAlphaInfo(self.CGImage)
);
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0.0, self.size.height *scaleFactor);
CGContextScaleCTM(context, 1.0 , -1.0);
CGAffineTransform transform = CGAffineTransformMakeScale(scaleFactor, scaleFactor);
[path applyTransform:transform];
if(invertPath){
UIBezierPath *rectPath = [UIBezierPath bezierPathWithRect:imageRect];
CGContextAddPath(context, rectPath.CGPath);
CGContextAddPath(context, path.CGPath);
CGContextEOClip(context);
} else {
CGContextAddPath(context, path.CGPath);
CGContextClip(context);
}
CGContextScaleCTM(context, 1.0, -1.0);
CGContextTranslateCTM(context, 0.0, -self.size.height * scaleFactor);
CGContextDrawImage(context, imageRect, [self CGImage]);
CGImageRef imageRef = CGBitmapContextCreateImage(context);
return [UIImage imageWithCGImage:imageRef scale:scaleFactor orientation:0];
}
#end
The following image was cropped twice with the same path. once inverted, once not inverted. than I merged them again.
NSString *imageName = #"IMG_2345.jpg";
UIImage *image = [UIImage imageNamed:imageName];
UIImage *image2 = [UIImage imageNamed:imageName];
CGSize size = CGSizeMake(320, 320 * image.size.height / image.size.width);
image = [image resizedImage:size interpolationQuality:kCGInterpolationHigh];
image2 = [image2 resizedImage:size interpolationQuality:kCGInterpolationHigh];
image2 = [image2 grayscaledImage];
image = [image imageCroppedWithPath:[self circlePathWithSize: circleSize] invertPath: NO];
image2 = [image2 imageCroppedWithPath:[self circlePathWithSize: circleSize] invertPath: YES];
It is on Github