Limit the Pan Gesture boundary of a UIImageView inside in a UIView - objective-c

Question

I'm using the below code
- (void)panGestureDetected:(UIPanGestureRecognizer *)recognizer
{
static CGRect originalFrame;
if (state == UIGestureRecognizerStateBegan)
{
originalFrame = recognizer.view.frame;
}
else if (state == UIGestureRecognizerStateChanged)
{
CGPoint translate = [recognizer translationInView:recognizer.view.superview];
CGRect newFrame = CGRectMake(fmin(recognizer.view.superview.frame.size.width - originalFrame.size.width, fmax(originalFrame.origin.x + translate.x,0.0)),
fmin(recognizer.view.superview.size.height - originalFrame.size.height, fmax(originalFrame.origin.y + translate.y, 0.0)),
originalFrame.size.width,
originalFrame.size.height);
recognizer.view.frame = newFrame;
}else if (state == UIGestureRecognizerStateEnded)
{
[self performSelectorInBackground:#selector(ChangeViewAlphaTo1) withObject:nil];
}
}

Answer 1

The main problem is that you are trying to solve two constraints in one line.
Try to break things down when you have an issue. Massive statements are hard to read and even harder to debug.
CGRect newFrame = CGRectMake(fmin(recognizer.view.superview.frame.size.width - originalFrame.size.width, fmax(originalFrame.origin.x + translate.x,0.0)),
fmin(recognizer.view.superview.size.height - originalFrame.size.height, fmax(originalFrame.origin.y + translate.y, 0.0)),
originalFrame.size.width,
originalFrame.size.height);
is barely readable and when you revisit this in 6 months time you or another coder will not be able to tell what you were trying to do.
try replacing that monster with…
[self translateView:recognizer.view limitedBySuperViewBounds:translate];
all of a sudden the method tells you what you are doing.
-(void)translateView:(UIView *)aview limitedBySuperViewBounds:(CGPoint)translate
{
CGRect frameToTranslate = aview.frame;
CGRect superviewBounds= aview.superview.bounds;
frameToTranslate.origin.x = frameToTranslate.origin.x + translate.x;
frameToTranslate.origin.y = frameToTranslate.origin.y + translate.y;
if (translate.x < 0) {
frameToTranslate.origin.x = 0;
}
else if (CGRectGetMaxX(frameToTranslate) > CGRectGetWidth(superviewBounds)){
frameToTranslate.origin.x = CGRectGetWidth(superviewBounds) - CGRectGetWidth(frameToTranslate);
}
if (translate.y < 0) {
frameToTranslate.origin.y = 0;
}
else if (CGRectGetMaxY(frameToTranslate) > CGRectGetHeight(superviewBounds)){
frameToTranslate.origin.y = CGRectGetHeight(superviewBounds) - CGRectGetHeight(frameToTranslate);
}
aview.frame = frameToTranslate;
}
This isn't just my opinion , this is Clean Code