I have a FooViewController that loads a FooView and then adds a TextField :
// FooViewController.m
#interface FooViewController () <UITextFieldDelegate>
#end
...
-(void)loadView {
CGRect aFrame = CGRectMake(160, 240, 100, 150);
FooView *fv = [[FooView alloc] initWithFrame:aFrame];
...
// TextField
CGRect tfRect = CGRectMake(50, 50, 150, 50);
UITextField *aTextField = [[UITextField alloc] initWithFrame:tfRect];
aTextField.borderStyle = UITextBorderStyleRoundedRect;
aTextField.returnKeyType = UIReturnKeyDone;
aTextField.delegate = self;
[fv addSubview:aTextField];
self.view = fv;
}
In this class implementation (FooViewController.m), I have the following method :
-(BOOL)textFieldShouldReturn:(UITextField *)textField {
return YES;
}
The whole code works well.
Just out of curiosity, I removed the <UITextFieldDelegate> mention and the textFieldShouldReturn is still get called.
How is that possible ?
That's okay,
There are 2 ways to implement safe delegating
1)
if ([self.delegate respondsToSelector:#selector(textFieldShouldReturn)]) {
[self.delegate textFieldShouldReturn];
}
2)
if ([self.delegate respondsToProtocol:#protocol(UITextFieldDelegate)]) {
[self.delegate textFieldShouldReturn];
}
Seems Apple uses first one, so your instance responds to textFieldShouldReturn and the call is made.
Objective-C is not as type-safe as other languages and does not care whether the delegate explicitly declares conformance using <UITextFieldDelegate>. The required delegate methods will be always called and if they are not implemented an exception will be thrown.
If your controller class (and its superclasses) do not declare <UITextFieldDelegate> then the following code should cause a compiler warning:
// warning that controller does not declare <UITextFieldDelegate>
textField.delegate = controller;
Note that with Swift this is no longer possible and will result in a compiler error instead.
Related
I need to subclass SVModalWebViewController.m (GitHub), which is itself a subclass of UINavigationController, and am incorporating this code into a new app that will be created entirely in Swift. I've run into several issues, so I decided to first convert just this very simple class into Swift to debug.
Initialization is a little different in Swift compared with Objective-C (read more about Swift initialization here), which is why I'm not returning self in the Swift code.
Here's the original Obj-C code (minus the *.h, which instantiates barsTintColor):
#import "SVModalWebViewController.h"
#import "SVWebViewController.h"
#interface SVModalWebViewController ()
#property (nonatomic, strong) SVWebViewController *webViewController;
#end
#implementation SVModalWebViewController
#pragma mark - Initialization
- (id)initWithAddress:(NSString*)urlString {
return [self initWithURL:[NSURL URLWithString:urlString]];
}
- (id)initWithURL:(NSURL *)URL {
self.webViewController = [[SVWebViewController alloc] initWithURL:URL];
if (self = [super initWithRootViewController:self.webViewController]) {
UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone
target:self.webViewController
action:#selector(doneButtonClicked:)];
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
self.webViewController.navigationItem.leftBarButtonItem = doneButton;
else
self.webViewController.navigationItem.rightBarButtonItem = doneButton;
}
return self;
}
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:NO];
self.webViewController.title = self.title;
self.navigationBar.tintColor = self.barsTintColor;
}
#end
And here's the entire Swift version of the class (I simplified to just one init method since I didn't need to init with URL specifically):
import UIKit
class SVModalWebViewController: UINavigationController {
var webViewController: SVWebViewController!
var barsTintColor: UIColor?
// This was added because of a compiler error indicating it needed to be added
init(nibName nibNameOrNil: String!, bundle nibBundleOrNil: NSBundle!) {
super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
}
init(address urlString: String!) {
let url: NSURL = NSURL.URLWithString(urlString)
self.webViewController = SVWebViewController(URL: url)
super.init(rootViewController: self.webViewController)
let doneButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Done, target: self.webViewController, action: Selector("doneButtonClicked:"))
if UIDevice.currentDevice().userInterfaceIdiom == .Pad {
self.navigationItem.leftBarButtonItem = doneButton
} else {
self.navigationItem.rightBarButtonItem = doneButton
}
}
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
// self.title may not be set, and is considered an optional in Swift, so we have to check first
if self.title {self.webViewController.title = self.title}
self.navigationBar.tintColor = self.barsTintColor
}
}
The issue I'm having relates to setting the Done button in the navigationItem. Currently they're not showing up at all when this code is called:
let webViewController = SVModalWebViewController(address: "http://www.google.com");
webViewController.barsTintColor = UIColor.blueColor()
self.presentModalViewController(webViewController, animated: true)
The modal view appears just fine and I'm able to correctly set the bar color property, but the Done button does not show up. It appears that I don't have proper access to the navigationItem of the UINavigationController. Note that I had to add the init with nibName method due to a compiler error without it. This wasn't required in the Obj-C code and I'll admit I'm not sure why it's needed in Swift - that could be part of the issue.
Any thoughts as to why I cannot set the self.navigationItem.leftBarButtonItem property of the UINavigationController? Thanks!
A UINavigationController does not have a navigationItem. Well, it does, but it's useless. It is the navigationItem of the child controller (in this case, the rootViewController, which you are also calling self.webViewController) that appears in the navigation bar.
I'm building a tag-based application and want to call the same function from each tab (ViewController).
I'm trying to do it in the following way:
#import "optionsMenu.h"
- (IBAction) optionsButton:(id)sender{
UIView *optionsView = [options showOptions:4];
NSLog(#"options view tag %d", optionsView.tag);
}
optionsMenu.h file:
#import <UIKit/UIKit.h>
#interface optionsMenu : UIView
- (UIView*) showOptions: (NSInteger) tabNumber;
#end
optionsMenu.m file:
#import "optionsMenu.h"
#implementation optionsMenu
- (UIView*) showOptions:(NSInteger) tabNumber{
NSLog(#"show options called");
UIView* optionsView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
optionsView.opaque = NO;
optionsView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5f];
//creating several buttons on optionsView
optionsView.tag = 100;
return optionsView;
}
#end
The result is that i never get the "show options called" debug message and thus optionsView.tag is always 0.
What am i doing wrong?
I understand this is most probably an easy and stupid question, but i am not able to solve it myself.
Any feedback is appreciated.
First thing to note is that this is an instance method (and not a Class method as described in the question title). This means that in order to call this method you should have alloc/init an instance of your Class and send the message to the instance. For example:
// Also note here that Class names (by convention) begin with
// an uppercase letter, so OptionsMenu should be preffered
optionsMenu *options = [[optionsMenu alloc] init];
UIView *optionsView = [options showOptions:4];
Now, if you just want to create a Class method that returns a preconfigured UIView, you could try something like this (provided that you do not need access to ivars in your method):
// In your header file
+ (UIView *)showOptions:(NSInteger)tabNumber;
// In your implementation file
+ (UIView *)showOptions:(NSInteger)tabNumber{
NSLog(#"show options called");
UIView *optionsView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
optionsView.opaque = NO;
optionsView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5f];
//creating several buttons on optionsView
optionsView.tag = 100;
return optionsView;
}
And finally send the message like this:
UIView *optionsView = [optionsMenu showOptions:4]; //Sending message to Class here
Finally do not forget of course to add your view as a subview in order to display it.
I hope that this makes sense...
I'm trying to do draw a fancy UIButton using Quartz. I've declared my own button class like this:
#interface MyButton : UIButton
#end
In the .m file I'm constructing the button:
- (id)initWithCoder:(NSCoder *)aDecoder
{
self = [super initWithCoder:aDecoder];
if (self) {
// Initialization code
CALayer *buttonLayer = self.layer;
buttonLayer.masksToBounds = YES;
CALayer *customDrawn = [CALayer layer];
customDrawn.delegate = self;
customDrawn.masksToBounds = YES;
[buttonLayer insertSublayer:customDrawn atIndex:0];
[customDrawn setNeedsDisplay];
}
return self;
}
But this results in some kind of recursion and finally fails with a EXC_BAD_ACCESS.
I've implemented a method drawLayer: inContext:, but it still crashes. The only way I can avoid the crash is by removing the delegate-assignment, but then I can't do any of the custom drawing I want to implement.
How can I make this work?
As described in the question mentioned by Kurt Revis, a UIView (such as UIButton) can't be used as a delegate for a sublayer. (It is already the delegate for the "main" layer of the UIView and can't be used as a delegate for another layer.) The solution is to use another object as a delegate which can be a "private" class just used to implement the drawLayer: inContext: method.
I have a strange problem that I've never encountered before,
I have data in my viewController that I want to display in a UIView.
It's an iPad App which involve a SplitView Controller, when I click on an element within the table view (masterView) it execute a function in my detailViewController (via a protocol).
A function is executed which launch a UIView and send data to it:
myController:
- (void)SelectionChanged:(DocumentInfo*)document_info withDocu:(Document *)document{
DocumentView *viewDoc=[[DocumentView alloc]initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.height)];
viewDoc.doc=document;
viewDoc.doc_info=document_info;
[viewDoc setBackgroundColor:[UIColor whiteColor]];
[self.view addSubview:viewDoc];
}
DocumentView.h
#import <UIKit/UIKit.h>
#import "Document.h"
#import "DocumentInfo.h"
#class Document;
#class DocumentInfo;
#interface DocumentView : UIView
#property(strong,nonatomic) Document *doc;
#property(strong,nonatomic) DocumentInfo *doc_info;
#end
DocumentView.m
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
UILabel *titreDoc=[[UILabel alloc] initWithFrame:CGRectMake(20, 32, 339, 21)];
titreDoc.textColor = [self makeColorRGB_RED:66 GREEN:101 BLUE:149];
titreDoc.font = [UIFont fontWithName:#"System" size:(24.0)];
[self addSubview:titreDoc];
NSLog(#"%# - %#",doc,doc_info);
titreDoc.text=#"Nouveau Document";
}
return self;
}
My view is well displayed (I mean the label appear) but impossible to get the data which would have been passed to it... (the NSLog print (null) (null) )
Anybody know the reason why?
The problem seems pretty straight forward. You initialize your view (which means that you run - (id)initWithFrame:(CGRect)frame) and after that you're setting the data, so it's normal that you see null values into your init method because the ivars have not being set yet. What you could do is to modify your init method in order to construct your view taking into account these ivars. Something like this perhaps:
- (id)initWithFrame:(CGRect)frame doc:(Document *)doc docInfo:(DocumentInfo *)docInfo;
ps. If you choose to make your custom init method do not forget to call the designated initializer (-initWithFrame:) before any customization.
The reason the NSLog prints null is because the doc and doc_info are nil when the initWithFrame method is called. The doc and doc_info properties are set after the initWithFrame method is called in selectionChanged: method. Add the NSLog function after line 3 in selectionChanged method like this:
- (void)SelectionChanged:(DocumentInfo*)document_info withDocu:(Document *)document{
DocumentView *viewDoc=[[DocumentView alloc]initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.height)];
viewDoc.doc=document;
viewDoc.doc_info=document_info;
NSLog(#"%# - %#",doc,doc_info);
[viewDoc setBackgroundColor:[UIColor whiteColor]];
[self.view addSubview:viewDoc];
}
I am creating a subclass of UIButton in order to create my own customized buttons. My code as follows:
//interface file (subclass of uIButton
#interface UICustomButton : UIButton
{
Answer *answer;
NSString *btnType;
}
#property (nonatomic, retain) Answer *answer;
#property (nonatomic, assign) NSString *btnType;
- (id)initWithAnswer:(Answer *)ans andButtonType:(NSString *)type andFrame:(CGRect)frame;
- (void)buttonPressed;
#end
//Implementation file (.m)
#implementation UICustomButton
#synthesize answer,btnType;
- (id)initWithAnswer:(Answer *)ans andButtonType:(NSString *)type andFrame:(CGRect)frame;
{
self = [super initWithFrame:frame];
if (self)
{
self = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];
self.backgroundColor = [UIColor colorWithHexString:#"#E2E4E7"];
}
[self addTarget:self action:#selector(buttonPressed) forControlEvents:UIControlStateNormal];
self.answer = ans;
self.btnType = type;
return self;
}
I am facing some issues in getting the above code to work. I have 2 problems
1) The buttons are not responding to the selector method "buttonPressed"
2) I am hitting a runtime error for the lines 'self.answer = ans' and 'self.btnType = type' Stack trace as follows:
-[UIButton setAnswer:]: unrecognized selector sent to instance 0x614ebc0
2011-06-23 00:55:27.038 onethingaday[97355:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIButton setAnswer:]: unrecognized selector sent to instance 0x614ebc0'
What am I doing wrong here?
This is happening because you are creating a UIButton type object and not a UICustomButton type inside the init method when you do
self = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];
Try replacing your init method for
- (id)initWithAnswer:(Answer *)ans andButtonType:(NSString *)type andFrame:(CGRect)frame;
{
self = [self initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];
if (self)
{
self.backgroundColor = [UIColor colorWithHexString:#"#E2E4E7"];
[self addTarget:self action:#selector(buttonPressed) forControlEvents:UIControlEventTouchUpInside];
self.answer = ans;
self.btnType = type;
}
return self;
}
This will cause self to be a UICustomButton type object.
Also, you are using a wrong type for the UIControlState parameter when you add the target to your button using the addTarget:action:forControlEvents: method
You should use value among the ones bellow:
UIControlEventTouchDown
UIControlEventTouchDownRepeat
UIControlEventTouchDragInside
UIControlEventTouchDragOutside
UIControlEventTouchDragEnter
UIControlEventTouchDragExit
UIControlEventTouchUpInside
UIControlEventTouchUpOutside
UIControlEventTouchCancel
EDIT:
Notes on UIButton subclassing
Many references on the web say you should NOT subclass the UIButton class, but not only anybody said why but what also deeply annoyed me was that the UIButton Class Reference does not say anything about it at all.
If you take UIWebView Class Reference for example, it explicitly states that you should not subclass UIWebView
Subclassing Notes The UIWebView class
should not be subclassed.
the big deal with UIButton is that it inherits from UIControl and a good and simple explanation is on the UIControl Class Reference itself
Subclassing Notes You may want to
extend a UIControl subclass for either
of two reasons:
To observe or modify the dispatch of
action messages to targets for
particular events
To provide custom
tracking behavior (for example, to
change the highlight appearance)
So, this means that you CAN subclass a UIButton, but you should be careful on what you are doing. Just subclass it to change its behavior and not its appearance. To modify a UIButton appearance you should use the interface methods provided for that, such as:
setTitle:forState:
setBackgroundImage:forState:
setImage:forState:
References worth reading
The UIView Programming Guide: View and Window Architecture -> Tips for Using Views Effectively -> Do Not Customize Controls by Embedding Subviews
Source: my post here
Not sure this was in the docs before, but anyway these are the current notes on + (id)buttonWithType:(UIButtonType)buttonType...
To me it looks like subclassing is OK as long as you use init instead of buttonWithType. I have yet to try it myself however.
Discussion This method is a convenience constructor for creating
button objects with specific configurations. It you subclass UIButton,
this method does not return an instance of your subclass. If you want
to create an instance of a specific subclass, you must alloc/init the
button directly.
When creating a custom button—that is a button with the type
UIButtonTypeCustom—the frame of the button is set to (0, 0, 0, 0)
initially. Before adding the button to your interface, you should
update the frame to a more appropriate value.
If you want to get notifications when the user is interacting with your buttons, just sublcass UIButton and implement these methods:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
NSLog(#"touchesBegan");
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
NSLog(#"touchesEnded");
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
NSLog(#"touchesCancelled");
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
NSLog(#"touchesMoved");
}
No init method required.
Edit
This answer reaches back several years, and things have changed - as Apple docs now explicitly mention subclassing and gives some hints.
So the following answer might be irrelevant or wrong for current development and might be ignored if you're interested in the current state of the art.
UIButton is not meant to be subclassed.
You are better off making a category and defining a factory method that delivers your needed button (with proper call to buttonWithType:). initWithFrame: is not the correct way to initialize a button anyway.
//
// BtnClass.m
#import "BtnClass.h"
#implementation BtnClass
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
//added custum properities to button
-(id)initWithCoder:(NSCoder *)aDecoder
{
NSLog(#"initWithCoder");
self = [super initWithCoder: aDecoder];
if (self) {
// Initialization code
_numberOfItems=[[UILabel alloc]initWithFrame:CGRectMake(40, 8, 160, 30)];
_numberOfItems.textAlignment=NSTextAlignmentLeft;
_numberOfItems.font = [UIFont boldSystemFontOfSize:18.0];
_numberOfItems.textColor = [UIColor darkGrayColor];
[self addSubview:_numberOfItems];
_leftImage=[[UIImageView alloc]initWithFrame:CGRectMake(10, 10, 25, 25)];
[self addSubview:_leftImage];
_rightImage=[[UIImageView alloc]initWithFrame:CGRectMake(280, 10, 15, 15)];
[self addSubview:_rightImage];
[self setImage:[UIImage imageNamed:#"list-bg2-1.png"] forState:UIControlStateNormal];
[_rightImage setImage:[UIImage imageNamed:#"carat.png"]];
self.backgroundColor=[UIColor blackColor];
if(self.tag==1)
{
[_leftImage setImage:[UIImage imageNamed:#"notes-icon.png"]];
}
if(self.tag==2)
{
[_leftImage setImage:[UIImage imageNamed:#"photos-icon.png"]];
}
if(self.tag==3)
{
[_leftImage setImage:[UIImage imageNamed:#"videos-icon.png"]];
}
}
return self;
}
//selected method of uibutton
-(void)setSelected:(BOOL)selected
{
[super setSelected:selected];
if(selected)
{
[self setImage:nil forState:UIControlStateNormal];
_numberOfItems.textColor = [UIColor whiteColor];
[_rightImage setImage:[UIImage imageNamed:#"carat-open.png"]];
if(self.tag==1)
{
[_leftImage setImage:[UIImage imageNamed:#"white-notes-icon.png"]];
}
else if(self.tag==2)
{
[_leftImage setImage:[UIImage imageNamed:#"white-photo-icon.png"]];
}
else
{
[_leftImage setImage:[UIImage imageNamed:#"white-video-icon.png"]];
}
}
else{
_numberOfItems.textColor = [UIColor darkGrayColor];
if(self.tag==1)
{
[_leftImage setImage:[UIImage imageNamed:#"notes-icon.png"]];
}
if(self.tag==2)
{
[_leftImage setImage:[UIImage imageNamed:#"photos-icon.png"]];
}
if(self.tag==3)
{
[_leftImage setImage:[UIImage imageNamed:#"videos-icon.png"]];
}
[self setImage:[UIImage imageNamed:#"list-bg2-1.png"] forState:UIControlStateNormal];
[_rightImage setImage:[UIImage imageNamed:#"carat.png"]];
}
}
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
}
*/
#end