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UIStackView programmatically

July 25, 2017Uncategorizedadmin

This project demonstrates how to:

– Create a UIStackView
– add uiviews to it
– add constraints to the uiviews
– make each uiview appear and disappear

http://angelolloqui.com/blog/36-Oddities-of-UIStackView
https://developer.apple.com/documentation/uikit/uiview/1622572-translatesautoresizingmaskintoco

Creating a constraint

Say you want to create a constraint. That constraints sits on constraint creation conveniences such as heightAnchor, widthAnchor, topAnchor, leftAnchor, etc. Any property that you can create a constraint on, that property will have an anchor you can access, and thus, create constraints from.

In our case, we want to to set a constraint to our height. Thus there is a heightAnchor. Access that property to create a constraint.

1	let heightConstraintA = a.heightAnchor.constraint(equalToConstant: 120.0)

translatesAutoresizingMaskIntoConstraints

From the doc: If you want to use Auto Layout to dynamically calculate the size and position of your view, you must set this property to false, and then provide a non ambiguous, nonconflicting set of constraints for the view.

1	a.translatesAutoresizingMaskIntoConstraints = false

By default, the property is set to true for any view you programmatically create.

If you add views in Interface Builder, the system automatically sets this property to false.

Resolving Constraint conflicts using priority

Thus, later on we’ll be hiding our viewA. However there is a constraint on viewA that says its height has to be 120, as stated earlier. In this case, we’ll get a constraint conflict in the log console, because setting aView’s isHidden to true, makes its height to 0. This is a constraint conflict with 120.

Thus, in order to fix this, we need to lower the priority of our 120 height constraint so that when viewA’s height changes to 0 (due to it being hidden), it will see that the 120 height constraint’s priority is lower. This is because any new height constraints has a default priority of 1000. Since 120 has a lower priority, then the constraints engine will allow 0 (which defaults to highest priority of 1000) to be valid.

let heightConstraintA = a.heightAnchor.constraint(equalToConstant: 120.0)

heightConstraintA.isActive = true

heightConstraintA.priority = 999

a.translatesAutoresizingMaskIntoConstraints = false

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import UIKit

when we set isHidden, the height is changed to 0.

http://angelolloqui.com/blog/36-Oddities-of-UIStackView

Basically, what happens here is that the stack view will automatically set your height to 0 (if vertical layout, or width if horizontal) when you make the view hidden. In the specific example attached above, the arranged view contains a segment control that has some extra padding of 8px by using required autolayout constraints. As a result, when the subview tries to resize to 0, the constraints with the padding can not be satisfied (requires a minimum of 16px size, but the stack wants to set it to 0), resulting in the above error. A way to solve it is to make sure that you have no size constraints like that, or if you need them, lower their priority so the AutoLayout engine will know which one to break (always yours). Have in mind that all the stackview managed constraints are required (priority 1000)

class ViewController: UIViewController {

var hideA = false

var hideB = false

var hideC = false

let stackView = UIStackView()

let a = UIView()

let b = UIView()

let c = UIView()

override func viewDidLoad() {

super.viewDidLoad()

a.backgroundColor = UIColor.red

let heightConstraintA = a.heightAnchor.constraint(equalToConstant: 120.0)

heightConstraintA.isActive = true

heightConstraintA.priority = 999

a.widthAnchor.constraint(equalToConstant: 320).isActive = true

a.translatesAutoresizingMaskIntoConstraints = false

let heightConstraintB = b.heightAnchor.constraint(equalToConstant: 120.0)

heightConstraintB.isActive = true

heightConstraintB.priority = 999

b.backgroundColor = UIColor.green

b.widthAnchor.constraint(equalToConstant: 320).isActive = true

b.translatesAutoresizingMaskIntoConstraints = false

let heightConstraintC = c.heightAnchor.constraint(equalToConstant: 120.0)

heightConstraintC.isActive = true

heightConstraintC.priority = 999

c.backgroundColor = UIColor.orange

c.widthAnchor.constraint(equalToConstant: 320).isActive = true

c.translatesAutoresizingMaskIntoConstraints = false

view.addSubview(stackView)

stackView.backgroundColor = UIColor.blue

stackView.addArrangedSubview(a)

stackView.addArrangedSubview(b)

stackView.addArrangedSubview(c)

stackView.axis = .vertical

stackView.distribution = .fill

stackView.translatesAutoresizingMaskIntoConstraints = false

let buttonA = UIButton()

buttonA.setTitle("toggle A", for: .normal)

buttonA.setTitleColor(UIColor.blue, for: .normal)

buttonA.backgroundColor = UIColor.brown

buttonA.frame = CGRect(x: 5, y: 520, width: 80, height: 30)

buttonA.addTarget(self, action: #selector(toggleA(_:)), for: .touchUpInside)

self.view.addSubview(buttonA)

let buttonB = UIButton()

buttonB.setTitle("toggle B", for: .normal)

buttonB.setTitleColor(UIColor.blue, for: .normal)

buttonB.backgroundColor = UIColor.brown

buttonB.frame = CGRect(x: 115, y: 520, width: 80, height: 30)

buttonB.addTarget(self, action: #selector(toggleB(_:)), for: .touchUpInside)

self.view.addSubview(buttonB)

let buttonC = UIButton()

buttonC.setTitle("toggle C", for: .normal)

buttonC.setTitleColor(UIColor.blue, for: .normal)

buttonC.backgroundColor = UIColor.brown

buttonC.frame = CGRect(x: 215, y: 520, width: 80, height: 30)

buttonC.addTarget(self, action: #selector(toggleC(_:)), for: .touchUpInside)

self.view.addSubview(buttonC)

}

func toggleA(_ sender: Any) {

hideA = !hideA

UIView.animate(withDuration: 0.3, animations: {

self.a.isHidden = self.hideA

})

}

func toggleB(_ sender: Any) {

hideB = !hideB

UIView.animate(withDuration: 0.3, animations: {

self.b.isHidden = self.hideB

})

}

func toggleC(_ sender: Any) {

hideC = !hideC

UIView.animate(withDuration: 0.3, animations: {

self.c.isHidden = self.hideC

})

}

override func didReceiveMemoryWarning() {

super.didReceiveMemoryWarning()

// Dispose of any resources that can be recreated.

}

Table within a table

July 24, 2017C/C++/Objective-Cadmin

table within a table

UITableViewDataSource’s cellForRowAtIndexPath

For a certain row, use your custom cell that has the tableview.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath

{

if(indexPath.row != 0) {

NSLog(@"%s", __FUNCTION__);

UITableViewCell *cell = (UITableViewCell*)[tableView dequeueReusableCellWithIdentifier:@"tvcItems"];

if(cell==nil) {

NSLog(@"%s - Creating new cell for index %lu", __FUNCTION__, indexPath.row);

cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault

reuseIdentifier: @"tvcItems"];

}

[cell.textLabel setText:[self.myData objectAtIndex:[indexPath row]]];

return cell;

}

else { // for row 0, we create another table inside the cell

NSLog(@"%s - Creating MyTableViewCell for cell # %lu", __FUNCTION__, indexPath.row);

static NSString *cellIdentifier = @"HistoryCell";

// Similar to UITableViewCell, but

MyTableViewCell *cell = (MyTableViewCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];

if (cell == nil) {

cell = [[MyTableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];

}

// Just want to test, so I hardcode the data

//cell.descriptionLabel.text = @"Testing";

return cell;

}

UITableViewDelegate’s heightForRowAtIndexPath

Make sure your table view delegate method heightForRowAtIndexPath is appropriate so people can see your custom cell.

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {

if(indexPath.row==0) {

return 300.0f;

} else {

return 86.0f;

The cell that contains the inner table

Create your tableview with its associated data array, then add it to the cell’s view hierarchy.

#import "MyTableViewCell.h"

@implementation MyTableViewCell

@synthesize dataArray; //array to hold submenu data

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier

{

self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];

if (self) {

[self setBackgroundColor:[UIColor orangeColor]];

self.frame = CGRectMake(0.0f, 20.0f, self.bounds.size.width, 300.0f);

self.dataArray = [[NSMutableArray alloc] initWithObjects:@"Inner Table - One", nil];

UITableView * subMenuTableView = [[UITableView alloc]initWithFrame:CGRectMake(0.0f, 20.0f, self.bounds.size.width, 280.0f)

style:UITableViewStylePlain]; //create tableview a

subMenuTableView.tag = 100;

subMenuTableView.delegate = self;

subMenuTableView.dataSource = self;

subMenuTableView.alwaysBounceVertical = NO;

[self addSubview:subMenuTableView]; // add it cell

...

}

-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView

{

return 1;

}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

{

return dataArray.count;

}

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath

{

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cellID"];

if(cell == nil)

{

cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cellID"];

}

cell.textLabel.text = [self.dataArray objectAtIndex:indexPath.row];

return cell;

}

...

Table row animation

July 24, 2017C/C++/Objective-Cadmin

Assuming you have basic table with data set up, this is how you do row animations on it.

To remove a row from the end

-(void) removeButtonClicked:(UIButton*)sender {

NSLog(@"you clicked on button %@", sender.titleLabel.text);

UITableView * subMenu = (UITableView*)[self viewWithTag:100];

[self.dataArray removeLastObject];

[subMenu deleteRowsAtIndexPaths:@[[NSIndexPath indexPathForRow:self.dataArray.count inSection:0]]

withRowAnimation:UITableViewRowAnimationTop];

}

To add a row to the end

-(void) addButtonClicked:(UIButton*)sender

{

NSLog(@"you clicked on button %@", sender.titleLabel.text);

[self.dataArray addObject:[NSString stringWithFormat:@"%lu", self.dataArray.count + 1]];

UITableView * subMenu = (UITableView*)[self viewWithTag:100];

//append row

[subMenu insertRowsAtIndexPaths:@[[NSIndexPath indexPathForRow:self.dataArray.count - 1 inSection:0]]

withRowAnimation:UITableViewRowAnimationTop];

}

To reload all sections in a table

-(void) reloadButtonClicked: (UIButton*)sender {

// no animation

NSLog(@"you clicked on button %@", sender.titleLabel.text);

UITableView * subTableView = (UITableView*)[self viewWithTag:100];

for (int i = 0; i < self.dataArray.count; ++i) {

// Select a random element between i and end of array to swap with.

int Elements = (int)self.dataArray.count - i;

int n = (arc4random() % Elements) + i;

[self.dataArray exchangeObjectAtIndex:i withObjectAtIndex:n];

}

NSIndexSet *sections = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, [subTableView numberOfSections])];

[subTableView reloadSections:sections withRowAnimation:UITableViewRowAnimationFade];

}

Move a row

// move data from the FROM location to the TO location

-(void) moveButtonClicked:(UIButton*)sender {

NSLog(@"you clicked on button %@", sender.titleLabel.text);

UITableView * subMenu = (UITableView*)[self viewWithTag:100];

// get the to location's data at the FROM

id data = [self.dataArray objectAtIndex:0];

// remove the that data

[self.dataArray removeObject:data];

// then insert the data to the TO location

[self.dataArray insertObject:data atIndex:self.dataArray.count];

// then just call the moveRowAtIndexPath

[subMenu moveRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]

toIndexPath:[NSIndexPath indexPathForRow:self.dataArray.count-1 inSection:0]];

}

clean architecture

July 19, 2017Uncategorizedadmin

Clean Swift iOS Architecture for Fixing Massive View Controller

Design pattern in ViewController, delegate, dataSource

July 18, 2017C/C++/Objective-Cadmin

ViewController.h

@interface TestViewController {

}

ViewController.m

The concept of delegate is that we can delegate messages to another object, as long as that object conforms to the delegate.
Once an object conforms to a delegate, it just simply needs to implement the delegate methods and that’s it.

Hence in our example, everything starts at tableView. tableView has 2 delegates:

UITableViewDelegate
UITableViewDataSource

Our ViewController class matches up with the ViewController box in the image. Then notice its 2 delegates coming out of it.

One is called “delegate”.
The other is called “dataSource”.

In code, looks like this:

@interface TestViewController ()

@property (weak, nonatomic, readwrite) IBOutlet UITableView *tableView;

@property (strong, nonatomic) TestDelegate *tableViewDelegate;

@property (strong, nonatomic) TestDataSource *tableViewDataSource;

@end

@implementation TestViewController

...

- (void)viewDidLoad

{

[super viewDidLoad];

self.tableViewDataSource = [[TestDataSource alloc] initWithController:self];

self.tableViewDelegate = [[TestDelegate alloc] initWithController:self];

self.tableView.delegate = self.tableViewDelegate;

self.tableView.dataSource = self.tableViewDataSource;

}

Those delegates must point to objects that conforms to them.
Therefore, we then have object TestDelegate that conforms to UITableViewDelegate, which means it implements UITableViewDelegate’s method(s).
Hence the “delegate” delegate can point to it.

Same thing for UITableViewDataSource’s method(s). Hence the “dataSource” delegate can point to it.

TestDataSource.h

TestDataSource conforms to the UITableViewDataSource,
so that TestViewController’s tableView’s dataSource delegate can point to it.

@interface TestDataSource : NSObject <UITableViewDataSource>

@property (strong, nonatomic, readonly) NSMutableDictionary *items;

@end

In the DataSource object, we have a data structure that represent the data we are going to represent on the table.

Initializing the cell object for data source’s cellForRowAtIndexPath

Naturally, when we implement cellForRowAtIndexPath in the data source, we ask the tableView to dequeue a reusable cell for us. Then simply
configure the cell with an “item” object. The reason for this is that we don’t want to initialize an cell object by using multiple parameters and pass lots of data into it.

// not what we want

TestCell *cell = [self.testController.tableView dequeueReusableCellWithIdentifier:[TestCell cellIdentifier]

forIndexPath:indexPath];

cell.propertyA = "this";

cell.propertyB = 234;

cell.propertyC = "wow";

// cell...

// goes on forever

return cell;

Rather, we create a configureWithItem that takes in an object type called say testItem. This is how we pass large amount of data into the cell.

Hence in your custom cell class, do something like this:

TestCell

@interface TestCell : UITableViewCell {

}

- (void)configureWithItem:(TestCellItem *)item;

@interface JNOneFieldCell () {

}

@property (strong, nonatomic) TestCellItem *item;

@end

- (void)configureWithItem:(TestCellItem *)item {

// this way, you can get all the data from an item object

self.item = item;

}

In your data source object, you have the item objects in a structure array. Using the row index, pluck the items from the array and initialize your cell objects with it.

@interface TestDataSource ()

@property (weak, nonatomic) TestViewController *testNowController;

@property (strong, nonatomic, readwrite) NSMutableDictionary *items;

@end

@implementation TestDataSource

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

TestCell *cell = [self.testController.tableView dequeueReusableCellWithIdentifier:[TestCell cellIdentifier]

forIndexPath:indexPath];

cell.delegate = self.testController;

[cell configureWithItem:self.items[@(indexPath.row)]];

return cell;

}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

return IHGJNCellsCount;

}

@end

TestDelegate

Say, in your delegate, you need to access the data that is being displayed on your table.

For example, you need to return 0 for the height on index 2’s row depending on index 2’s data.
So how do you get that data?

The concept is to access the tableView’s dataSource. Only the viewController has the reference to the tableView.
Thus that is why we have a reference to the viewController as a property, and initialized it via dependency injection like so:

@interface TestDelegate

@property (weak, nonatomic) TestViewController *joinNowController;

@end

@implementation TestDelegate

- (instancetype)initWithController:(TestViewController *)controller {

self = [super init];

if (self) {

self.joinNowController = controller;

}

return self;

}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {

}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

}

@end

Now that you have reference to testNowController, you can then get the data source like this:

1	TestDataSource *dataSource = self.testNowController.tableView.dataSource;

Then all you need to do is access the items array in the dataSource, and you can get the data from the row:

- (id)dataItemForIndexPath:(NSIndexPath *)indexPath

{

TestDataSource *dataSource = self.testNowController.tableView.dataSource;

return [dataSource.items objectForKey:@(indexPath.row)];

}

Make sure your return is id, because the array contains different kind of “item” objects. i.e.

TestAItem
TestBItem
TestCItem

Now you can access the item object for that index. Check for a property in the item. Then return the height accordingly.

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {

TestAItem * testItem = [self p_itemFromDataSourceForIndexPath:indexPath];

if(testItem.isVisible==NO) {

return 0;

} else {

return 60.0f;

}

Protected: 19651 – notes

July 5, 2017Projectsadmin

Static methods vs class methods

July 5, 2017Uncategorizedadmin

https://stackoverflow.com/questions/29636633/static-vs-class-functions-variables-in-swift-classes

static and class both associate a method with a class, rather than an instance of a class.

The difference is that subclasses can override class methods; they cannot override static methods.

Cannot override final functions