I've implemented an UICollectionView with a custom layout. It adds a decoration view to the layout. I use the following code to add layout attributes of the decoration view:
-(NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
{
NSArray *allAttributes = [super layoutAttributesForElementsInRect:rect];
return [allAttributes arrayByAddingObject:[self layoutAttributesForDecorationViewOfKind:kHeaderKind atIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]]];
}
The data in the collection view is provided by a NSFetchedResultsController.
Now it looked likes it worked fine, but when the collection view is empty, it fails because there's section 0. Tried to use it without an index path, but fails too. Any thoughts on how to use decoration views in an empty UICollectionView? Should be possible since decoration views aren't data-driven.
When using a decoration view or a supplemental view not attached to a specific cell, use [NSIndexPath indexPathWithIndex:] to specify the index path. Here is a sample code:
#interface BBCollectionViewLayout : UICollectionViewFlowLayout
#end
#implementation BBCollectionViewLayout
- (void)BBCollectionViewLayout_commonInit {
[self registerClass:[BBCollectionReusableView class] forDecorationViewOfKind:BBCollectionReusableViewKind];
}
- (id)initWithCoder:(NSCoder *)aDecoder {
if ((self = [super initWithCoder:aDecoder])) {
[self BBCollectionViewLayout_commonInit];
}
return self;
}
- (id)init {
self = [super init];
if (self) {
[self BBCollectionViewLayout_commonInit];
}
return self;
}
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect {
NSMutableArray *array = [NSMutableArray arrayWithArray:[super layoutAttributesForElementsInRect:rect]];
UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForDecorationViewOfKind:BBCollectionReusableViewKind atIndexPath:[NSIndexPath indexPathWithIndex:0]];
if (CGRectIntersectsRect(rect, attributes.frame)) {
[array addObject:attributes];
}
return array;
}
- (UICollectionViewLayoutAttributes *)layoutAttributesForDecorationViewOfKind:(NSString*)elementKind atIndexPath:(NSIndexPath *)indexPath {
UICollectionViewLayoutAttributes *attributes = [UICollectionViewLayoutAttributes layoutAttributesForDecorationViewOfKind:elementKind withIndexPath:indexPath];
attributes.frame = CGRectMake(0., 60., 44., 44.);
return attributes;
}
#end
I created and tested this simple example that seems to work in iOS 7 in all possible situations (0 sections, 1 section with 0 items etc). This is my layout class, subclass of UICollectionViewFlowLayout. The rest of the project is just scaffolding.
#import "JKLayout.h"
#import "JKDecoration.h"
#implementation JKLayout
- (instancetype)init
{
if (self = [super init]) {
[self registerClass:[JKDecoration class] forDecorationViewOfKind:#"Decoration"];
}
return self;
}
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
{
NSArray *allAttributes = [super layoutAttributesForElementsInRect:rect];
// It’s important to set indexPath to nil. If I had set it to indexPath 0-0, it crashed with InternalInconsistencyException
// because I was trying to get decoration view for section 0 while there in reality was no section 0
// I guess if you need to have several decoration views in this case, you’d identify them with a method other than indexpath
return [allAttributes arrayByAddingObject:[self layoutAttributesForDecorationViewOfKind:#"Decoration" atIndexPath:nil]];
}
- (UICollectionViewLayoutAttributes *)layoutAttributesForDecorationViewOfKind:(NSString *)decorationViewKind atIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewLayoutAttributes *attr = [super layoutAttributesForDecorationViewOfKind:decorationViewKind atIndexPath:indexPath];
if (!attr) {
attr = [UICollectionViewLayoutAttributes layoutAttributesForDecorationViewOfKind:decorationViewKind withIndexPath:indexPath];
attr.frame = CGRectMake(0, 200, 100, 100);
}
return attr;
}
#end
Related
I have a tabbed view controller and I put a table view in it but when I run the program I got this EXC_BAD_ACCESS signal.
The array does not get loaded and produces this error.
Here is my code:
ContactsViewController.h
#import <UIKit/UIKit.h>
#interface ContactsViewController : UITableViewController <UITableViewDataSource,UITableViewDelegate>
#property (nonatomic ,retain) NSArray *items;
#end
ContactsViewController.m
#import "ContactsViewController.h"
#interface ContactsViewController ()
#end
#implementation ContactsViewController
#synthesize items;
- (id)initWithStyle:(UITableViewStyle)style {
self = [super initWithStyle:style];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad {
[super viewDidLoad];
items = [[NSArray alloc] initWithObjects:#"item1", #"item2", "item3", nil];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [items count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"cell"];
if (cell == nil) {
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"cell"];
}
return cell;
}
#end
The problem with your code lies (as the debugger tells you) in the following line:
items = [[NSArray alloc] initWithObjects:#"item1", #"item2", "item3", nil];
Take a closer look at "item3". There is no # sign in front of it so it is not an NSString object but a plain old C string. You can only put objects into an NSArray.
Change it to
items = [[NSArray alloc] initWithObjects:#"item1", #"item2", #"item3", nil];
or even simpler
item = #[#"item1", #"item2", #"item3"];
Without the rest of the code it's not possible to say for sure what the problem is, but you should access the variable through the property in the following way.
self.items = ...
Also consider using the shorthand array notation, like this.
self.items = #[#"Item 1", #"Item 2", #"Item 3"];
IMO: The only time you should use variables directly is in an overriden property accessory.
Also note that if you do want to use the variable directly you should change the synthesize command to the following #synthesize items = variableName; This puts a name, variableName on the underlying variable used in the property. You can then access the variable without going through the property.
I am trying to achieve this:
but i get this:
I have a view cotroller with a view table on it
This is the interface:
#interface LoginViewController : UIViewController<UITableViewDataSource, UITableViewDelegate>
#property (weak, nonatomic) IBOutlet UITableView *tblCredentials;
#end
This is the implementation:
#interface LoginViewController ()
#end
#implementation LoginViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
}
-(void)viewWillAppear:(BOOL)animated
{
self.tblCredentials.delegate=self;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 2;
}
// Row display. Implementers should *always* try to reuse cells by setting each cell's reuseIdentifier and querying for available reusable cells with dequeueReusableCellWithIdentifier:
// Cell gets various attributes set automatically based on table (separators) and data source (accessory views, editing controls)
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"CellIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
UITextField *textField = [[UITextField alloc] init];
textField.enablesReturnKeyAutomatically = YES;
textField.autocorrectionType = UITextAutocorrectionTypeNo;
textField.autocapitalizationType = UITextAutocapitalizationTypeNone;
CGRect cellBounds = cell.bounds;
CGFloat textFieldBorder = 10.f;
CGRect aRect = CGRectMake(textFieldBorder, 9.f, CGRectGetWidth(cellBounds)-(2*textFieldBorder), 31.f );
textField.frame = aRect;
if(indexPath.row==0)
{
textField.placeholder = #"Username";
textField.returnKeyType = UIReturnKeyNext;
textField.autocapitalizationType = UITextAutocapitalizationTypeWords;
}
else
{
textField.placeholder = #"Password";
textField.returnKeyType = UIReturnKeyDone;
textField.secureTextEntry = YES;
}
[cell.contentView addSubview:textField];
return cell;
}
#end
I put a breakpoint on the in the cellForRowAtIndexPath and it doesn't stop there, so those text fields don't get rendered.
What am I missing?
PS: Is this a bad approach to achieve the goal? (those two grouped text fields)
LE: I am using stroyboard with no xib files
In viewDidLoad, you must set the delegate and call [self.tblCredentials reloadData] in order for the table view to actually "load its data"
You need to create a Custom Table View cell. have a look at this github link.
You're setting the delegate of the table view, but not the datasource, which is where the number of rows etc. comes from.
You're also setting the delegate a bit late in the cycle. Since this is in a xib, why not set the delegate and datasource in the xib instead of in code? If you declare that your view controller conforms to the delegate and data source properties in the header, you will be able to make the connection in IB. If you insist on setting it in code, it should be in viewDidLoad.
Set delegate and dataSource in -viewDidLoad and put [self.tblCredentials reloadData] in -viewWillAppear:.
- (void)viewDidLoad
{
[super viewDidLoad];
self.tblCredentials.delegate=self;
self.tblCredentials.dataSource=self;
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated]; // BTW, it's better to call super's -viewWillAppear: here, according to apple's documentation.
[self.tblCredentials reloadData];
}
It's stepping into the ViewDidLoad of the main view controller, and hitting the line calling get all tweets, but I put a breakpoint in the getAllTweets of both the base and derived to see if it just wasn't hitting the derived like I expected.
#implementation WWMainViewControllerTests {
// system under test
WWMainViewController *viewController;
// dependencies
UITableView *tableViewForTests;
WWTweetServiceMock *tweetServiceMock;
}
- (void)setUp {
tweetServiceMock = [[WWTweetServiceMock alloc] init];
viewController = [[WWMainViewController alloc] init];
viewController.tweetService = tweetServiceMock;
tableViewForTests = [[UITableView alloc] init];
viewController.mainTableView = tableViewForTests;
tableViewForTests.dataSource = viewController;
tableViewForTests.delegate = viewController;
}
- (void)test_ViewLoadedShouldCallServiceLayer_GetAllTweets {
[viewController loadView];
STAssertTrue(tweetServiceMock.getAllTweetsCalled, #"Should call getAllTweets on tweetService dependency");
}
- (void)tearDown {
tableViewForTests = nil;
viewController = nil;
tweetServiceMock = nil;
}
The base tweet service:
#implementation WWTweetService {
NSMutableArray *tweetsToReturn;
}
- (id)init {
if (self = [super init]) {
tweetsToReturn = [[NSMutableArray alloc] init];
}
return self;
}
- (NSArray *)getAllTweets {
NSLog(#"here in the base of get all tweets");
return tweetsToReturn;
}
#end
The Mock tweet service:
#interface WWTweetServiceMock : WWTweetService
#property BOOL getAllTweetsCalled;
#end
#implementation WWTweetServiceMock
#synthesize getAllTweetsCalled;
- (id)init {
if (self = [super init]) {
getAllTweetsCalled = NO;
}
return self;
}
- (NSArray *)getAllTweets {
NSLog(#"here in the mock class.");
getAllTweetsCalled = YES;
return [NSArray array];
}
The main view controller under test:
#implementation WWMainViewController
#synthesize mainTableView = _mainTableView;
#synthesize tweetService;
NSArray *allTweets;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
allTweets = [tweetService getAllTweets];
NSLog(#"was here in view controller");
}
- (void)viewDidUnload
{
[self setMainTableView:nil];
[super viewDidUnload];
// Release any retained subviews of the main view.
}
Since you're able to break in the debugger in viewDidLoad, what's the value of the tweetService ivar? If it's nil, the getAllTweets message will just be a no op. Maybe the ivar isn't being set properly or overridden somewhere else.
You should probably use the property to access the tweetService (call self.tweetService) rather than its underlying ivar. You should only ever access the ivar directly in getters, setters, and init (also dealloc if aren't using ARC for some crazy reason).
You also should not call loadView yourself, rather just access the view property of the view controller. That will kick off the loading process and call viewDidLoad.
Also, if you're doing a lot of mocking, I highly recommend OCMock.
I'm trying to subclass NSTokenField to intercept some of the keyboard events. I wrote subclasses for NSTokenField, NSTokenFieldCell and NSTextView. In the NSTokenField subclass I swap the regular cell with my custom cell and in the custom cell I override -(NSTextView*)fieldEditorForView:(NSView *)aControlView to provide my textview as a custom field editor. All the initialisation methods are called as expected but for some reason my custom token field is not drawn.
Here is the code for the NSTokenField subclass:
#synthesize fieldEditor = _fieldEditor;
-(JSTextView *)fieldEditor
{
if (!_fieldEditor) {
_fieldEditor = [[JSTextView alloc] init];
[_fieldEditor setFieldEditor:YES];
}
return _fieldEditor;
}
- (void)awakeFromNib {
JSTokenFieldCell *newCell = [[JSTokenFieldCell alloc] init];
[self setCell:newCell];
}
+ (Class) cellClass
{
return [JSTokenFieldCell class];
}
- (id)initWithFrame:(NSRect)frameRect
{
self = [super initWithFrame:frameRect];
if (self) {
JSTokenFieldCell *newCell = [[JSTokenFieldCell alloc] init];
[self setCell:newCell];
}
return self;
}
-(id)initWithCoder:(NSCoder *)aDecoder
{
self = [super initWithCoder:aDecoder];
if (self) {
JSTokenFieldCell *newCell = [[JSTokenFieldCell alloc] initWithCoder:aDecoder];
[self setCell:newCell];
}
return self;
}
And here is the code for the subclass of NSTokenFieldCell:
-(NSTextView*)fieldEditorForView:(NSView *)aControlView
{
if ([aControlView isKindOfClass:[JSTokenField class]]) {
JSTokenField *tokenField = (JSTokenField *)aControlView;
return tokenField.fieldEditor;
}
return nil;
}
- (id)initWithCoder:(NSCoder *)decoder
{
return [super initWithCoder:decoder];
}
- (id)initTextCell:(NSString *)aString
{
return [super initTextCell:aString];
}
- (id)initImageCell:(NSImage *)anImage
{
return [super initImageCell:anImage];
}
Addition
After further digging I found this post which says that the only way to have an NSTokenField with a custom text view is by overriding private methods. Is it true? If so, is there any other way I can intercept keyboard events without subclassing NSTextView?
I am creating a Two Level table view. And the second view is supposed to have the list of the movies I have listed below in my viewDidLoad method, but it is not showing.(You can see my screen shots attached)Does anyone know which file where I can look to see why it is not showing? The code below is from my DisclosureButtonController.m file which is to display this information after I hit the Disclosure Buttons instance on the First Level screen.
Regards,
#import "LWWDisclosureButtonController.h"
#import "LWWAppDelegate.h"
#import "LWWDisclosureDetailController.h"
#interface LWWDisclosureButtonController ()
#property (strong, nonatomic) LWWDisclosureDetailController *childController;
#end
#implementation LWWDisclosureButtonController
#synthesize list;
#synthesize childController;
//- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
//{
// self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
//if (self) {
// Custom initialization
//}
//return self;
//}
- (void)viewDidLoad
{
[super viewDidLoad];
NSArray *array = [[NSArray alloc] initWithObjects:#"Toy Story", #"A Bug's Life", #"Toy Story 2", #"Monsters, Inc.", #"Finding Nemo", #"The Incredibles", #"Cars", #"Ratatouille", #"WALL-E", #"Up", #"Toy Story 3", #"Cars 2", #"Brave", nil];
self.list = array;
// Do any additional setup after loading the view.
}
- (void)viewDidUnload
{
[super viewDidUnload];
self.list = nil;
self.childController = nil;
// Release any retained subviews of the main view.
}
#pragma mark -
#pragma mark Table Data Source Methods
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [list count];//
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath: (NSIndexPath *)indexPath
{
static NSString * DisclosureButtonCellIdentifier = #"DisclosureButtonCellIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:DisclosureButtonCellIdentifier];
if (cell == nil)
{
cell = [[UITableViewCell alloc]
initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:DisclosureButtonCellIdentifier];
}
NSUInteger row = [indexPath row];
NSString *rowString = [list objectAtIndex:row];
cell.textLabel.text = rowString;
cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton;
return cell;
}
#pragma mark -
#pragma mark Table Delegate Methods
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Hey, boss do you see the disclosure button?" message:#"If you're trying to drill down, touch that instead mate!" delegate:nil cancelButtonTitle:#"Won't happen again" otherButtonTitles:nil];
[alert show];
}
- (void)tableView:(UITableView *)tableView accessoryButtonTappedForRowWithIndexPath: (NSIndexPath *)indexPath
{
if (childController == nil)
{
childController = [[LWWDisclosureDetailController alloc]initWithNibName:#"LWWDisclosureDetail" bundle:nil];
}
childController.title = #"Disclosure Button Pressed";
NSUInteger row = [indexPath row];
NSString *selectedMovie = [list objectAtIndex:row];
NSString *detailMessage = [[NSString alloc]initWithFormat:#"You pressed the disclosure button for %#.", selectedMovie];
childController.message = detailMessage;
childController.title = selectedMovie;
[self.navigationController pushViewController:childController animated:YES];
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
#end
Why not start the array with the VC instead of after the VC loads? Try overriding the init method.
- (id) init {
if((self == [super init])) {
//load your array here and set
}
return self;
}
That way, on older devices, you don't have to wait after the view loads to see the array. But, however, this is my preference. I love to override init methods and create my own.
Also, for some weird reason on my SDK, I have to use NSMutableArray instead of NSArray or it won't work. Maybe you have the same issue?
Also, I've noticed NSString *selectedMovie. Instead of using just "row", use the getter indexPath.row.
Hope these suggestions helped!
Call:
[self.tableView reloadData]; (put in place of self.tableView the var or property connected to the tableView)
after the:
self.list = array;
code line in the viewDidLoad method
and put a
NSLog(#"number of rows: %d", [self.list count]);
in
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [list count];//
}
to check if it is not zero.