It's simple. You have many many views inside your controller. You change the frame of one of them. You breath. And then you have to manually update every single frame on the hierarchy to fill the missing gap.
ETFlowView is an automatic layout engine, so every single subview will be updated when the frame of a view in the hierarchy is changed.
As a web or Android developer, you must be surprised that this project even exists, since Apple should have implemented it many many years ago.
Clone this repo and copy the folder ETFlowView into your Xcode project.
ETFlowView can be user both programmatically or loaded automatically from a nib.
If you are going to load it from a nib, just load a standard UIScrollView from the elements panel and change its class to ETFlowView:
If you need to reference it on code, just make an IBOutlet out of it:
@property (strong, nonatomic) IBOutlet ETFlowView *view;
Programmatically, just alloc it and set its frame:
[[ETFlowView alloc] initWithFrame:CGRectMake(0.0, 0.0, self.view.frame.size.width, self.view.frame.size.height)];
The recommended way is to manually update the hierarchy. To do this, just call - (void)updateView:(UIView *)view toFrame:(CGRect)newFrame; with the updated size of any view. You can use sizeThatFits: to help on your frame's calculations, but don't forget to call the aforementioned method.
Otherwise, if you want KVO enabled on every view of the hierarchy, you should set _shouldBind to YES. On this mode, all elements will be automatically bound whenever you call addSubView or removeFromSuperview. Unfortunatelly, Apple's implementation doesn't follow keyPath:frame properly, so missed calls occur frequently.
Everytime a view is resized, ETFlowView will update its contentSize property to fit the content if fitFrameToContentSize is set to YES.
Remember that, if your element is absolute positioned, it will not be affected by the algorithm. That's very important, since sometimes designers want to build very complex layouts that do not make sense programatically. Here is an example:
If view B is resized, it will not affect any of the elements on view A. That happens because view B is not a child neither a parent of view A (it's actually a sibling), which means it is absolute positioned and will not affect any of its siblings.
If you wish to use a matrix oriented design, with elements on both sides, feel free to enable _isMatrix to YES. It will recalculate your grid for every call, which is perfect for squared or rectangular layouts!
If you would like some wrappers to help with resizing texts or using pre-defined heights, try ETFlowView+Resize.h and ETFlowView+Text.h. Just import them in your class and use their available methods.
- Make sure you master view is visible before resizing it. Otherwise, the algorithm will not now if your view is one of Apple's hidden ones or a true one you have specified.
Just open an issue on Github and we'll get to it as soon as possible.
ETFlowView is brought to you by Trilha.