How to zoom into a selected area of image in iPhone?

问题

I have an ImageView when clicked on that imageview, transparent circle should be created and again when double clicking on that circle, particular Image in that circle area should be zoomed.Any suggestion would be appreciated.

回答1:

I think this code will helpfull to you

- (id)initWithImage:(UIImage *)image {
    self = [super initWithImage:image];
    if (self) {
        [self setUserInteractionEnabled:YES];

        UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
        UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];
        UITapGestureRecognizer *twoFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTwoFingerTap:)];

        [doubleTap setNumberOfTapsRequired:2];
        [twoFingerTap setNumberOfTouchesRequired:2];

        [self addGestureRecognizer:singleTap];
        [self addGestureRecognizer:doubleTap];
        [self addGestureRecognizer:twoFingerTap];

        [singleTap release];
        [doubleTap release];
        [twoFingerTap release];
    }
    return self;
}

#pragma mark Private

- (void)handleSingleTap:(UIGestureRecognizer *)gestureRecognizer {
    if ([delegate respondsToSelector:@selector(tapDetectingImageView:gotSingleTapAtPoint:)])
        [delegate tapDetectingImageView:self gotSingleTapAtPoint:[gestureRecognizer locationInView:self]];
}

- (void)handleDoubleTap:(UIGestureRecognizer *)gestureRecognizer {
    if ([delegate respondsToSelector:@selector(tapDetectingImageView:gotDoubleTapAtPoint:)])
        [delegate tapDetectingImageView:self gotDoubleTapAtPoint:[gestureRecognizer locationInView:self]];
}

- (void)handleTwoFingerTap:(UIGestureRecognizer *)gestureRecognizer {
    if ([delegate respondsToSelector:@selector(tapDetectingImageView:gotTwoFingerTapAtPoint:)])
        [delegate tapDetectingImageView:self gotTwoFingerTapAtPoint:[gestureRecognizer locationInView:self]];
}

来源：https://stackoverflow.com/questions/18800754/how-to-zoom-into-a-selected-area-of-image-in-iphone