I want to create an UIView Class that you can initialise with several options.
I think the problem is the drawRect() method. Is it possible to initialise the class with a certain option like
[[MyUIView alloc]initWithColor:[UIColor blueColor]]
I read that I should never call the drawRect() method without initialising an object.
So how can I realize the statement above without calling it manually?
What I have tried so far:
I thought that I could just initialize the View and then call Method
[MyView changeColorTo:green]
which tries to redraw the View however I couldn't get that to work.
Maybe it's important that I draw with coreGraphics (with a certain color, which should be selectable) a rounded rectangle in the drawRect() method.
How can I implement my desired behaviour?
call
[self setNeedsDisplayInRect:aCGRect];
that calls drawRect: for you.
Edit on the color property:
#interface MyView: UIView
#property (nonatomic, strong) UIColor *drawColor;
#end
#implementation MyView
#synthesize drawColor;
- (id)initWithWhatever
{
self.drawColor = [UIColor infraRedColor];
[self setNeedsDisplayInRect:aRect];
}
- (void)drawRect:(CGRect)r
{
// use self.drawColor
}
#end
Related
I am learning OpenGLES and I am trying to put a GLKViewer inside an UIViewController.
I know I can come around the main issues by using GLViewController, but I am trying to learn how to do it this way.
I found this question, Nesting GLKView into UIViewController and Nested GLKView and GLKViewController but I must be missing something even though I think I am doing all the right steps because when I run my project, I am not getting to the drawInRect print line.
In the storyboard I am pointing the ViewController as the delegate of the glkview component.
I tried to keep the code as simple as possible and any help will be apreciated:
MyController.h
#import <Foundation/Foundation.h>
#import <GLKit/GLKit.h>
#interface MyGLController : UIViewController <GLKViewDelegate>
{
GLuint vertexBufferID;
}
#property (weak, nonatomic) IBOutlet GLKView *glview;
#property (strong, nonatomic) GLKBaseEffect *baseEffect;
#end
MyGLController.m
#import "MyGLController.h"
#implementation MyGLController
//#synthesize baseEffect;
-(void) viewDidLoad{
[super viewDidLoad];
self.glview.context = [[EAGLContext alloc] initWithAPI:
kEAGLRenderingAPIOpenGLES2];
[EAGLContext setCurrentContext:self.glview.context];
printf("View Loaded");
}
- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect
{
printf("DrawInRect");
}
#end
* Update *
As far as I can tell the glkview is hooked up properly as suggested per and added the josh-knapp and called setNeedsDisplay.
In case there's something I am missing, I have uploaded a copy of the project here: https://github.com/jcrogel/OpenGLDebug.git
I am a total noob in this so I apologize for any silly oversight :)
You didn't say you hooked up the glview property of MyGLController in the storyboard, so verify that.
Next, you're setting up the glview context after it loads. Without a GLKViewController, there is nothing telling the glview it needs to be drawn. Make sure you call [self.glview setNeedsDisplay] somewhere after the context is set up.
I had a similar problem.
By default, xcode sets the enable setNeedsDisplay checkbox to NO in GLKView property list.
Once I changed it, it worked.
I see this question was already answered. But I had the same problem, with a different solution. I figured I'd post the info here on the off chance others might be able to benefit from it.
Problem Description
While using GLKView and GLKViewController, the render loop function (drawInRect) is called once, but not called again.
Possible Cause
Some methods to CViewController have been implemented incorrectly, without calling their supers. The following code illustrates three such functions. The examples below have the three functions implemented correctly, calling their supers.
-(void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:NO];
}
-(void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:NO];
}
-(void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:NO];
}
I'm thinking of a way to have a UIView render itself onto another UIView as well as the first one. So I have my main UIView with it's bounds, and the UIView also renders itself in some other UIView.
Is this possible ? Does it require extensive layer operations?
Don't know whats your real intention is, but this will draw the view twice, userinteraction etc. will not work on the second view. Also this solution does not take care of different frame sizes.
Header of the View you want to clone
#interface SrcView : UIView
#property(nonatomic, readonly, strong) UIView *cloneView;
#end
#interface CloneView : UIView
#property(nonatomic, weak) UIView *srcView;
- (id)initWithView:(UIView *)src;
#end
implementation of the View you want to clone
#import "SrcView.h"
#import "CloneView.h"
#implementation SrcView
#synthesize cloneView;
- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx{
[cloneView setNeedsDisplay];
}
- (UIView *)cloneView {
if (!cloneView) {
cloneView = [[CloneView alloc] initWithView:self];
}
return cloneView;
}
#end
#implementation CloneView
#synthesize srcView;
- (id)initWithView:(UIView *)src {
self = [super initWithFrame:src.frame];
if (self) {
srcView = src;
}
return self;
}
- (void)drawRect:(CGRect)rect
{
[srcView.layer renderInContext:UIGraphicsGetCurrentContext()];
}
#end
now you can just call cloneView and add it somewhere you want.
This seems to be an oft asked question here on StackOverflow. For example:
iphone, ipad Duplicate UIView - Cloned View
Copying the drawn contents of one UIView to another
UIView duplicate
Duplicate, clone or copy UIView
But if it were me doing this, my first approach would be to get a handle to the UIView I want to copy, then recursively iterate all the subviews of it and then copy & add them as subviews to the UIView I want to copy the main UIView into.
I can't imagine there's too much layer operations going on with this, but you would likely need to figure out how to programmatically re-establish outlets and/or actions.
There is no easy way to clone a view and then to update two views by one line of code. Because their underlying CALayers are different. But for duplicating a UIView, here is a new method you can use: Use UIView's method:
- (UIView *)snapshotViewAfterScreenUpdates:(BOOL)afterUpdates
This is the fastest way to draw a view. Available in iOS 7.
Create another instance of the UIView you wish to "clone" and add it as a subview to another view. You don't really clone a UIView object, you simply create another instance of it.
I know how to create a protocol already but I'm wondering what would be the best practice to create a proxy protocol like Apple did for the UIAppearance protocol and the implementation on certain UI classes.
Why I want to do it this way? Because I already have a lot of UI classes and I would like to centralize the implementation of the code for changing color.
Maybe an odd question but my curiosity drove me to this point.
Thanks
Just make the proxy a static object and access it through class-level methods, the same way you'd implement a singleton, e.g.
#implementation MyClass
+ (MyProxyObject *)proxy
{
static MyProxyObject *sharedProxy = nil;
if (sharedProxy == nil)
{
sharedProxy = [[MyProxyObject alloc] init];
}
return sharedProxy;
}
#end
Then for any property of your class, e.g. textColor, just have your class use the value in [[self class] proxy].textColor instead of storing its own value. E.g.
#interface MyClass : UIView
#property (nonatomic, strong) textColor
#end
#implementation MyClass
- (UIColor *)textColor
{
return textColor ?: [[self class] proxy].textColor
}
#end
If you need a way to refresh your onscreen views immediately whenever a property on the proxy is changed, you could do that by having the proxy broadcast an NSNotification in its textColor setter method, and have all the instances observe that notification and call setNeedsDisplay on themselves when they receive it.
I had thought I actually had a pretty good handle on the whole view controller model, but something just doesn't seem to making much sense for me. My main issue is with adding a custom UIView subclass as a property of a UIViewController subclass.
Whenever I assign a valid instance of a UIView subclass to that property, nothing happens or the code crashes.
Here's a quick outline:
The main controller inits its own view and that loads fine.
I can then add this UIView subclass to the main controller by instantiating it and addSubview:ivar etc. No problems there...
However... if I wanted to have this custom UIView as a property of the ViewController, that does not seem to work. Can anyone shed some light?
Here's a code summary:
#interface CustomUIView : UIView { }
.
#interface MainViewController : UIViewController {
CustomUIView *someOtherView;
}
#property (nonatomic, copy) CustomUIView *someOtherView;
...
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor greenColor]; // the default controller view
CustomUIView *tmpView = [[CustomUIView alloc] initWithFrame:CGRectMake(0,0,320,480)];
[self.view addSubview:tmpView]; // this works
self.someOtherView = tmpView; // this does NOT work and
self.view = self.someOtherView; // ultimately, this is what i'm after
[tmpView release];
}
Many thanks to this wonderful community!
You can't copy UIViews. Or UIView subclasses. Try retain, instead.
I was just wondering if this approach looks like a good practice for apps with a lot of custom views, for nested PNG graphics and animations that may change based on user interaction. I created a BaseView class that extends UIView
#interface BaseView : UIView {
#protected
BaseViewController *controller;
}
#property (retain) BaseViewController *controller;
#end
and a corresponding controller class which is the primary location which I am putting code to manipulate the view
#interface BaseViewController : UIViewController {
#protected
CGRect drawArea;
}
- (void) drawArea:(CGRect) _drawArea;
- (CGRect) drawArea;
- (void) linkSubviewController: (BaseViewController *) _subviewController;
#end
where "drawArea" is the CGRect used to pass to the view as a frame.
"linkSubviewController" allows you to nest a controller and view as follows :
- (void) linkSubviewController: (BaseViewController *) _subviewController {
[self.view addSubview:[_subviewController view]];
}
In addition I layered another custom pair called "ImageView" and "ImageViewController" which extend BaseView but also store a UIImage and an x,y,w,h
In the "drawRect" drawing methods on views I can check to see if any vars in the self.controller vars have been changed, or assign images, for example :
UIImage *image = [(ImageViewController *)self.controller image];
CGContextDrawImage( ... ) etc
I write most of the loadView methods something like this
- (void)loadView {
ImageView *v = [[ImageView new] initWithFrame:drawArea];
v.controller = self;
self.view = v;
}
The base "initWithFrame" routine contains
self.backgroundColor = [UIColor clearColor];
self.opaque = NO;
So I can load a variety of images with transparent backgrounds without having to assign that each time.
I've been able to use this code throughout my app and it seems to make it easy to write a top level class which assembles the layout of custom items. For animations I've been putting them in the controllers and manipulating self.view.layer.
Basically I am looking for feedback, I am new with Objective-C and the IPhone SDK
There are several issues here:
Using [[Classname new] init...] is incorrect usage of new. Using new is short for [[Classname alloc] init] so you are effectively calling init twice.
Views shouldn't really need to know who is controlling them.
Your view is retaining the controller, and since UIViewController retains its view, you have a retain cycle and neither will ever be fully released.
If you want this type of behavior (whereby a view can delegate its drawing to a parent), try creating a DrawDelegate protocol, have your controllers implement that protocol, and in your view subclass have a non-retaining drawDelegate property:
#protocol DrawDelegate
- (void) drawArea:(CGRect)rect;
#end
#interface BaseView : UIView {
id<DrawDelegate> drawDelegate;
}
#property (assign) id<DrawDelegate> drawDelegate;
#end