PECropViewController *controller = [[PECropViewController alloc] init];
 controller.delegate = self;
 controller.image = self.imageView.image;
 
 UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:controller];
 [self presentViewController:navigationController animated:YES completion:NULL];

self.cropView = [[PECropView alloc] initWithFrame:contentView.bounds];
[self.view addSubview:self.cropView];

- (void)cropViewController:(PECropViewController *)controller didFinishCroppingImage:(UIImage *)croppedImage
{
    [controller dismissViewControllerAnimated:YES completion:NULL];
    self.imageView.image = croppedImage;
}

UIImage *croppedImage = self.cropView.croppedImage;

controller.keepingCropAspectRatio = YES;

self.cropView.keepingCropAspectRatio = YES;

// e.g.) Cropping center square
CGFloat width = image.size.width;
CGFloat height = image.size.height;
CGFloat length = MIN(width, height);
controller.imageCropRect = CGRectMake((width - length) / 2,
                                      (height - length) / 2,
                                      length,
                                      length);

// e.g.) Cropping center square
CGFloat width = image.size.width;
CGFloat height = image.size.height;
CGFloat length = MIN(width, height);
self.cropView.imageCropRect = CGRectMake((width - length) / 2,
                                         (height - length) / 2,
                                         length,
                                         length);

[controller resetCropRect];

[self.cropView resetCropRect];