I have an app which allows users to send messages to each. The process is accomplished by saving the sent messages in a local SQLite database, while actually sending the messages to a database and using push notifications to send the message to the recipient's SQLite database. The set up I have works fine. However, what I am confused about is how to set up the actual interactive UI for the user (I am using XCode). I figured it should be a UITableView with each table cell representing a message. However, with this approach I run into a few requirements:
Variable TextView Sizes
Just as with regular iOS messaging, the TextView's size needs to be variable, adjusting its dimensions to fit all of the text in each message. I do not know how to accomplish this. I have a general understanding of how to generally vary sizes, but no clue how to dynamically have it based on the text within that view.
Variable TextView Positions
Again, just as with regular iOS messaging, the textview needs to be offset to either the right or left side depending on whether the sender was the user or who the are conversing with, respectively. I also do not know how to do this, because it changes the center of the textview.
Non-selectability
Xcode allows cells to be pressed. Handling what happens after this selection can be achieved by the didSelectRowatIndexPath tableView function. I can simply not implement this, but clicking on the cell causes it to turn darker to indicate it has been pressed. I would like to eliminate this while retaining the ability to, say, select some of the text and copy and paste it or whatever (just like messaging works normally on your phone).
Other Approaches?
This is the real meat of the question. I have considered the above approach because that is all that I have been able to come up with based on my limited experience with XCode UI elements. If there is a better approach (perhaps even a pod or framework) for this purpose I would love to hear it. I do not need the messaging UI to look amazing, just clean and crisp.
I suggest the following:
Variable TextView Sizes:
I assume you do use auto layout. If you don’t yet, please consider using it since it make life much easier!
If you use a UITableView, you can adjust the height of its UITableViewCells dynamically, depending on the actual content by using self-sizing cells. You can find a tutorial how to do this here.
Variable TextView Positions:
I assume you have a UITextView within a table view cell. In this case, you have to set auto layout constraints to the borders of the cell’s contentView. If you define a custom subclass of a UITableViewCell, you can define in this class 2 IBOutlet properties that are linked to say the left and the right layout constraints (e.g. var leftLayoutConstraint: NSLayoutConstraint). Then, you can set the constraint’s constant property as required when the cell is laid out, i.e. in the layoutSubviews function of the custom table view cell.
Non-selectability:
I am not sure what you mean by „I can simply not implement this“. Please make sure that you set the delegate property of the UITableView to the view controller where you want to handle cell selection. Selecting a cell changes the cells color by default, but you can change this: In the storyboard, select your table view’s prototype cell, and open Xcode’s utility pane (top rightmost button). Under „Table view cell“ you find „Selection“ that you can set to „None“.
I hope this helps!
Related
I understand that you cannot call view(atColumn:row:makeIfNecssary:) from within tableView(_:heightRow:).
Ideally I'd like to derive height based on a button state within the NSTableCellView. I can think of a couple ways to work around this.
Use objectValue in my custom NSTableCellView to keep track of the state of the button.
Only enable buttons on selected row items and maintain a list of the selected NSTableCellView.
Are these recommended or is there another recommended way to handle this.
Also, is it recommended for a NSTableCellView to know what row/col it belongs too? Or is this something that also should be maintained in objectValue?
My use case is will have a disclosure arrow to expand the cell. I've tested it out and it works, however at this point, I'm using a test flag variable to control the height values not the actual button state.
I am a rookie Cocoa guy. I need to design and implement a view which will show collection of labels on Mac OS using Xamarin. These labels will have a text and color associated with them. When shown inside the view, label should expand till it covers whole text and it will be shown with background and foreground colors.
I have attached the picture of this user control on Windows, you can see that labels inside the StackPanel are expanding till they cover the whole text. Hope this gives better idea about my ask.
The $64,000 question is "are these labels controls?" In other words, do you expect the user to click on these to do something, or are they just for display?
If your answer is "just for display", the solution is super simple: Use an NSTextField and programmatically add attributed text (NSAttributedString) to it. Attributed text attaches display properties to runs of text within the field; properties like "background color".
If you want these to be buttons that you can click on, then things get a lot more complicated.
Since you apparently want the button layout to "flow", you might look into imbedding buttons (well, button cells) into an NSTextField using attachments. This is normally how non-text content (say, an image) can be inserted, but with some fiddling it can actually be anything a control cell can draw. See How to insert a NSButton into a NSTextView? (inline).
Warning: this is not a "rookie" topic and will involve control cells and custom event handling.
If I were doing this, I'd probably just create NSButton objects for each label (choosing an appropriate style/look like NSRecessedBezelStyle), create a custom subclass of NSView to contain them, and then override the layout method to position all of the buttons the way I want.
To be thorough, I'd also override the intrinsic size methods so the whole thing could participate in auto-layout, based on the number and size of buttons it contained.
I am Creating a tableview using custom cell with textfield. When i enter text in tableviewcell textfield and when i scroll the tableview the data is changing . Means re painting cells . How can i stop reloading cell on drag or scroll in IOS 8 swift
Thanks
If your want your cell not re-used, try to make it a subclass of UITableViewCell with a unique identifier, and do not use the identifier with other cells. I haven't test it yet, just hope it will solve your problem.
Ps. If the textfield's text is still overwritten, make a check at the cell's class file (like making an if-else statement checking if the textfield's text is empty).
Detailed workflow:
In cellForRowAtIndexPath(), after you dequeue the cell, normally you will set some property of your custom cell to refresh the data it holds. To implement this, you need to add a didSet observer on the property at the cell's class file. To achieve the goal you want, you can also add the checking code in the didSet observer.
In Your case. You need to customize your keyboard.
Add [Prev][Next] buttons on top of the keyboard and avoid scrolling.
Basically this idea is useful in form based app. May be your doing that kind.
And yes, Stop relaoding of cells is not good to app. If you will implement this. Apple will not approve your app. So avoid this kind of stuffs.
This is how cells work in a UITableView. The standard implementation of the cellForRowAtIndexPath: method dequeues cells and reuses them.
And ideally your app should save the text from the text fields and change the correct text in the cells depending on their indexPath in the same method's implementation.
If you do not want to do that, a dirty workaround would be to create a new cell every time in the cellForRowAtIndexPath: method instead of dequeuing rows.*
*Do not do this unless absolutely necessary. This is very bad coding practice
I've been reading through the Apple documentation about NSButtons and cells and I really can't seem to understand the distinction between the two. Adding to this complexity, it looks like both of them have a large overlap of methods like setTitle: etc. and I'm not sure which ones I should use.
Can anyone explain what the basic differences are?
Thanks,
Teja
You can think of a control as a cell's representative, or "agent".1 The control is an NSView, which means two important things in these circumstances. First, that it represents an area of a window to be drawn in. Second, that it accepts user interaction.2
The control doesn't do very much itself, though. The cell is the thing that does all the work -- notice, for example, that cells can draw themselves into a given frame. This is the responsibility of a view, but the control defers that to the cell, simply providing an area for drawing.
Likewise, when a user clicks on a control, the control receives the event and figures out what it means, but the work of performing an action in response to the event is passed on to the cell.
If you look at the docs for various control/cell pairs (NSButton and NSButtonCell being one such pair), you will see mention of "cover" methods. This means that the control has methods with the same names as its counterpart cell, which simply call through to the cell's. That's the source of the duplication that you mentioned. When you want to use one of these methods, call it on the control -- as the public face of the pair, it will most likely simply ask the cell anyways.
The best Apple-provided description of the interaction is "How Controls and Cells Interact" in the Control and Cell Programming Topics guide.
1In the sense of a actor having an agent who procures gigs.
2This is not strictly true of all views; it's actually a feature of NSResponder from which NSView inherits.
Excerpted from Cocoa Programming for OS X: The Big Nerd Ranch Guide
“A cell handles the implementation details of the control. For the
most part, the cell’s properties and methods are “covered” by
identical properties and methods in the corresponding control. For
instance, when you change the title on a label, the label’s cell is
doing the work, but you interact with the label’s stringValue
property.
Cells have a long history in Cocoa. They were originally
added to address performance issues: many of the basic tasks of a
control were handed off to the cell, which could do them more
efficiently than the control.
Mac computers are much more powerful
than they were in those days, and cells have become an encumbrance.
Apple has stated that it is in the process of deprecating cells, but
you will still see them in your document outline and in older code.”
NSButtonCell is a subclass of NSActionCell used to implement the user interfaces of push buttons, switches, and radio buttons. It can also be used for any other region of a view that's designed to send a message to a target when clicked.
The NSButton subclass of NSControl uses a single NSButtonCell. To create groups of switches or radio buttons, use an NSMatrix holding a set of NSButtonCells.
NSButton Cell has alot more cutomizable options for drawing and behaviour. The differences are better seen in the classes they inherit from (NSButtonCell inherits from the ActionCell class, while the NSButton inherits from the NSControl class.
Take a look at the documentation better:
http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ApplicationKit/Classes/NSButton_Class/Reference/Reference.html
http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ApplicationKit/Classes/NSButtonCell_Class/Reference/Reference.html
You should choose based on how you want the buttons to be drawn and behave. If its a simple button you want, use NSButton.
I have an NSCollectionView that I want to accept items dragged from elsewhere in my application.
I implement collectionView:validateDrop:proposedIndex:dropOperation: and collectionView:acceptDrop:index:dropOperation: in the collectionview's delegate and register for the appropriate dragged types. Both methods get called fine when I drag the appropriate types, but I don't get a blue focus ring over the collectionview indicating a valid drag.
Have tried both the collection view and its containing scroll view on Default and External settings for the focus ring. Both are just the standard non-derived Cocoa classes. Wondered if there was anything else I should try. Surely it isn't necessary to subclass NSCollectionView for this?
Thanks
Chris
Focus rings are not typically the correct way to provide feedback about drag destinations. Every view does it slightly differently. NSTextView shows the insertion bar. NSTableView shows a blue line in between rows for Before drop operations, and shows a bezel around the row for On drop operations. (See NSTableViewDropOperation)
NSCollectionView shows a "gap" between existing subviews to show where the items will be dropped for Before drop operations, and it will set the selected property on NSCollectionViewItem to YES for On drop operations. (Note: NSCollectionViewItem doesn't do anything by default to visibly represent the selected property. You must implement that yourself.)
Since NSCollectionView's feedback uses existing subviews only, it appears there isn't any feedback at all for empty NSCollectionView's. You would need to subclass to provide this behavior yourself. You could also file a bug to request that NSCollectionView do this itself.