I am on OSX, XCode 8.3.3, Objective-C.
I have subclassed NSView* to set a custom background color:
.h
#interface SHViewWhiteBackground : NSView
#property NSColor* backgroundColor;
#end
.m
#implementation SHViewWhiteBackground
- (void)drawRect:(NSRect)dirtyRect {
NSColor* fillColor = [NSColor whiteColor];
if (self.backgroundColor)
fillColor = self.backgroundColor;
[fillColor setFill];
NSRectFill(dirtyRect);
[super drawRect:dirtyRect];
}
#end
Now i can call
[view setBackgroundColor:[NSColor someColor]];
[view setNeedsDisplay:YES];
to change the color. I was wondering if there is a way to animate that change?
I ended up using layer backed views and the pop framework for animation.
I was trying to implement a project with custom navigation bar; however, the following code:
#implementation UINavigationBar (CustomImage)
// Set the navigation bar background
- (void)drawRect:(CGRect)rect {
UIImage *image = [UIImage imageNamed:#"TopBar.png"];
[image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height + 1)];
}
#end
is not working for iOS 5. I am using Xcode 4.2.
Question: How can I implement a custom navigation bar without compromising the use of the code above for earlier versions (< iOS 5)?
Any help would be appreciated. :)
I finally got it...this might help others implementing this.
#implementation UINavigationBar (CustomImage)
// Set the navigation bar background
- (UIImage *)barBackground{
UIImage *image = [UIImage imageNamed:#"TopBar.png"];
[image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height + 1)];
return image;
}
- (void)didMoveToSuperview{
// Applies to iOS 5
if ([self respondsToSelector:#selector(setBackgroundImage:forBarMetrics:)])
{
[self setBackgroundImage:[self barBackground] forBarMetrics:UIBarMetricsDefault];
}
}
// This doesn't work on iOS5 but is needed for iOS4 and earlier
- (void)drawRect:(CGRect)rect
{
// Draw the image
[[self barBackground] drawInRect:rect];
}
#end
I have been using this method to convert a UIView into UIImage. i.e. screen snapshot of a view -
#interface UIView(Extended)
- (UIImage *) imageByRenderingView;
#end
#implementation UIView(Extended)
- (UIImage *)imageByRenderingView
{
UIGraphicsBeginImageContext(self.bounds.size);
[self.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultingImage;
}
#end
To use it, I do this -
UIImage *currImage = [self.view imageByRenderingView];
This gives the image representation of the entire UIView. Now I want 2 images, one is of the top half of the UIView and the other is the bottom half. How do I do that?
You can split your UIImage in two by using this code:
CGImageRef topOfImageCG =
CGImageCreateWithImageInRect(currImage.CGImage,
CGRectMake(0,
0,
currImage.size.width,
currImage.size.height / 2.0));
UIImage *topOfImage = [UIImage imageWithCGImage:topOfImageCG];
CGImageRelease(topOfImageCG);
I need to replicate the effect that the UIButton does on an image when tapped, the highlighting. See:
The original PNG is a square with alpha background. When I set it as UIButton's image it automatically apply an effect on the non-alpha pixels of the image.
How to do this effect?
You could achieve this with a simple category on UIImage:
#interface UIImage (Tint)
- (UIImage *)tintedImageUsingColor:(UIColor *)tintColor;
#end
#implementation UIImage (Tint)
- (UIImage *)tintedImageUsingColor:(UIColor *)tintColor {
UIGraphicsBeginImageContextWithOptions(self.size, NO, self.scale);
CGRect drawRect = CGRectMake(0, 0, self.size.width, self.size.height);
[self drawInRect:drawRect];
[tintColor set];
UIRectFillUsingBlendMode(drawRect, kCGBlendModeSourceAtop);
UIImage *tintedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return tintedImage;
}
#end
For the effect shown above, you'd pass something like [UIColor colorWithWhite:0.0 alpha:0.3] as the tintColor parameter (experiment with the alpha value).
I try the following code, but it doesn't work.
[helloToolbar setBackgroundColor:[UIColor clearColor]];
To make a completely transparent toolbar, use the method described here. In a nutshell, create a new TransparentToolbar class that inherits from UIToolbar, and use that in place of UIToolbar.
TransarentToolbar.h
#interface TransparentToolbar : UIToolbar
#end
TransarentToolbar.m
#implementation TransparentToolbar
// Override draw rect to avoid
// background coloring
- (void)drawRect:(CGRect)rect {
// do nothing in here
}
// Set properties to make background
// translucent.
- (void) applyTranslucentBackground
{
self.backgroundColor = [UIColor clearColor];
self.opaque = NO;
self.translucent = YES;
}
// Override init.
- (id) init
{
self = [super init];
[self applyTranslucentBackground];
return self;
}
// Override initWithFrame.
- (id) initWithFrame:(CGRect) frame
{
self = [super initWithFrame:frame];
[self applyTranslucentBackground];
return self;
}
#end
(code from the blog post linked above)
In iOS 5, simply call setBackgroundImage and pass a transparent image.
Here's how I do it (I dynamically generate transparent image):
CGRect rect = CGRectMake(0, 0, 1, 1);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [[UIColor clearColor] CGColor]);
CGContextFillRect(context, rect);
UIImage *transparentImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[toolbar setBackgroundImage:transparentImage forToolbarPosition:UIToolbarPositionAny barMetrics:UIBarMetricsDefault];
The best you can do is using
[helloToolbar setBarStyle:UIBarStyleBlack];
[helloToolbar setTranslucent:YES];
This will get you a black but translucent toolbar.
Transparent (iOS 5.0):
[toolbar setBackgroundImage:[[UIImage alloc] init] forToolbarPosition:UIToolbarPositionAny barMetrics:UIBarMetricsDefault];
Translucent:
[toolbar setBarStyle:UIBarStyleBlack];
[toolbar setTranslucent:YES];
A cumulative solution for all devices, from oldest iOS 3.0 (iPhone 1) to newest iOS 6.1 (iPad mini).
#implementation UIToolbar (Extension)
- (void)drawRect:(CGRect)rect
{
if (CGColorGetAlpha(self.backgroundColor.CGColor) > 0.f)
{
[super drawRect:rect];
}
}
- (void)setTransparent
{
//iOS3+
self.backgroundColor = [UIColor clearColor];
//iOS5+
if ([self respondsToSelector:#selector(setBackgroundImage:forToolbarPosition:barMetrics:)])
{
[self setBackgroundImage:[[UIImage new] autorelease] forToolbarPosition:UIToolbarPositionAny barMetrics:UIBarMetricsDefault];
}
//iOS6+
if ([self respondsToSelector:#selector(setShadowImage:forToolbarPosition:)])
{
[self setShadowImage:[[UIImage new] autorelease] forToolbarPosition:UIToolbarPositionAny];
}
}
#end
When you want a transparent toolbar, call setTransparent on it.
When you want a non-transparent toolbar, set a backgroundColor of your choice or add an imageView by yourself.
Another solution would be to define a category for UIToolbar:
#implementation UIToolbar(Transparent)
-(void)drawRect:(CGRect)rect {
// do nothing in here
}
#end
In the IB set the toolbar as Black Translucent and non opaque.
We've just noticed that overriding drawRect doesn't work anymore with iOS 4.3. It's not called anymore (edit: seems to be only in Simulator). Instead drawLayer:inContext: is called.
A great solution was posted here
Now you can set each UIToolbar object transparent, by setting its tintColor to [UIColor clearColor] :)
With iOS 5 the following works:
UIToolbar *bar = [[UIToolbar alloc] initWithFrame:CGRectZero];
if (bar.subviews.count > 0)
[[[bar subviews] objectAtIndex:0] removeFromSuperview];
This is because the background is now a subview. This code is safe even with new iterations of iOS, but it may stop working. This is not private API usage, your app is safe to submit to the store.
Make sure you remove the backgroundView before adding any UIBarButtonItems to the bar. Or my code will not work.
I just tested the following with iOS 4.3 on simulator and phone, seems to work fine. Subclass UIToolbar, provide one method:
- (void)drawRect:(CGRect)rect
{
[[UIColor colorWithWhite:0 alpha:0.6f] set]; // or clearColor etc
CGContextFillRect(UIGraphicsGetCurrentContext(), rect);
}
toolbar.barStyle = UIBarStyleBlackTranslucent;
This works in iOS5.1 with pretty minimal effort. I am matching up the size, as only the background will have the same frame size as the toolbar itself. You could use other criteria, of course.
Enjoy.
Create a subclass of UIToolbar as follows:
.h:
#import <UIKit/UIKit.h>
#interface UIClearToolbar : UIToolbar
#end
.m:
#import "UIClearToolbar.h"
#implementation UIClearToolbar
- (void)layoutSubviews {
// super has already laid out the subviews before this call is made.
[self.subviews enumerateObjectsUsingBlock:^(UIView* obj, NSUInteger idx, BOOL *stop) {
if (CGSizeEqualToSize(self.frame.size, obj.frame.size) ||
self.frame.size.width <= obj.frame.size.width) { // on device, the background is BIGGER than the toolbar.) {
[obj removeFromSuperview];
*stop = YES;
}
}];
}
#end
Thanks #morais for your solution - here's the code translated to MonoTouch:
public class TransparentToolbar : UIToolbar
{
public TransparentToolbar()
{
init();
}
public TransparentToolbar(RectangleF frame) : base(frame)
{
init();
}
void init()
{
BackgroundColor=UIColor.Clear;
Opaque=false;
Translucent=true;
}
public override void Draw(RectangleF rect)
{
}
}