How to crop image inside the circle in UIImageView in iOS

Question

I have an app where I have a UIImageView which displays main image and another UIImageView being used as a mask which shows a circle which is trans

Answer 1

Same code reused to play with Square, it may be helpful for other.

#import "ViewController.h"

@interface ViewController () 

@property (weak, nonatomic) IBOutlet UIImageView *imageView;

@property (nonatomic) CGFloat circleRadius;
@property (nonatomic) CGPoint circleCenter;
@property (nonatomic) CGRect frame;


@property (nonatomic, weak) CAShapeLayer *maskLayer;
@property (nonatomic, weak) CAShapeLayer *circleLayer;

@property (nonatomic, weak) UIPinchGestureRecognizer *pinch;
@property (nonatomic, weak) UIPanGestureRecognizer   *pan;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    // create layer mask for the image

    CAShapeLayer *maskLayer = [CAShapeLayer layer];
    self.imageView.layer.mask = maskLayer;
    self.maskLayer = maskLayer;

    // create shape layer for circle we'll draw on top of image (the boundary of the circle)

    CAShapeLayer *circleLayer = [CAShapeLayer layer];
    circleLayer.lineWidth = 3.0;
    circleLayer.fillColor = [[UIColor clearColor] CGColor];
    circleLayer.strokeColor = [[UIColor blackColor] CGColor];
    [self.imageView.layer addSublayer:circleLayer];
    self.circleLayer = circleLayer;

    // create circle path

    [self updateCirclePathAtLocation:CGPointMake(self.view.bounds.size.width / 2.0, self.view.bounds.size.height / 2.0) radius:self.view.bounds.size.width * 0.30];

    // create pan gesture

    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
    pan.delegate = self;
    [self.imageView addGestureRecognizer:pan];
    self.imageView.userInteractionEnabled = YES;
    self.pan = pan;

    // create pan gesture

    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinch:)];
    pinch.delegate = self;
    [self.view addGestureRecognizer:pinch];
    self.pinch = pinch;
}

- (void)updateCirclePathAtLocation:(CGPoint)location radius:(CGFloat)radius
{
    self.circleCenter = location;
    self.circleRadius = radius;
    self.frame =CGRectMake(self.circleCenter.x/2, self.circleCenter.y/2, self.circleRadius, self.circleRadius);
    UIBezierPath *path =     [UIBezierPath bezierPathWithRoundedRect:self.frame cornerRadius:0];
//    [path addArcWithCenter:self.circleCenter
//                    radius:self.circleRadius
//                startAngle:0.0
//                  endAngle:M_PI * 2.0
//                 clockwise:YES];


    self.maskLayer.path = [path CGPath];
    self.circleLayer.path = [path CGPath];
}

- (IBAction)didTouchUpInsideSaveButton:(id)sender
{
    NSString *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
    NSString *path = [documentsPath stringByAppendingPathComponent:@"image.png"];

    CGFloat scale  = [[self.imageView.window screen] scale];

    CGRect frame = CGRectMake(self.frame.origin.x *scale,
                              self.frame.origin.y *scale,
                              self.frame.size.width*scale,
                              self.frame.size.width*scale);

    // temporarily remove the circleLayer

    CALayer *circleLayer = self.circleLayer;
    [self.circleLayer removeFromSuperlayer];

    // render the clipped image

    UIGraphicsBeginImageContextWithOptions(self.imageView.frame.size, NO, 0.0);
    CGContextRef context = UIGraphicsGetCurrentContext();
    if ([self.imageView respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)])
    {
        // if iOS 7, just draw it

        [self.imageView drawViewHierarchyInRect:self.imageView.bounds afterScreenUpdates:YES];
    }
    else
    {
        // if pre iOS 7, manually clip it

        CGContextAddRect(context, self.frame);
        CGContextClip(context);
        [self.imageView.layer renderInContext:context];
    }

    // capture the image and close the context

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    // add the circleLayer back

    [self.imageView.layer addSublayer:circleLayer];

    // crop the image
    NSLog(@"circle fram %@",NSStringFromCGRect(frame));
    NSLog(@"self fram %@",NSStringFromCGRect(self.frame));

    CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], frame);
    UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];

    // save the image

    NSData *data = UIImagePNGRepresentation(croppedImage);
    [data writeToFile:path atomically:YES];

    // tell the user we're done

    [[[UIAlertView alloc] initWithTitle:nil message:@"Saved" delegate:nil cancelButtonTitle:nil otherButtonTitles:@"OK", nil] show];
}


#pragma mark - Gesture recognizers

- (void)handlePan:(UIPanGestureRecognizer *)gesture
{
    static CGPoint oldCenter;
    CGPoint tranlation = [gesture translationInView:gesture.view];

    if (gesture.state == UIGestureRecognizerStateBegan)
    {
        oldCenter = self.circleCenter;
    }

    CGPoint newCenter = CGPointMake(oldCenter.x + tranlation.x, oldCenter.y + tranlation.y);

    [self updateCirclePathAtLocation:newCenter radius:self.circleRadius];
}

- (void)handlePinch:(UIPinchGestureRecognizer *)gesture
{
    static CGFloat oldRadius;
    CGFloat scale = [gesture scale];

    if (gesture.state == UIGestureRecognizerStateBegan)
    {
        oldRadius = self.circleRadius;
    }

    CGFloat newRadius = oldRadius * scale;

    [self updateCirclePathAtLocation:self.circleCenter radius:newRadius];
}


#pragma mark - UIGestureRecognizerDelegate

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    if ((gestureRecognizer == self.pan   && otherGestureRecognizer == self.pinch) ||
        (gestureRecognizer == self.pinch && otherGestureRecognizer == self.pan))
    {
        return YES;
    }

    return NO;
}

@end