Notes of a Developer » UIKit

ScrollView with scroll’s indicators, which are shown all the time.

Vladimir Boychentsov — Thu, 22 Dec 2011 09:53:13 +0000

My simple solution by writing category for UIImageView, because scroller is imageview.

How to use :)
Just setup tag for your scrollview and you will get one with scroll indicators, which are shown all the time.

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#define noDisableVerticalScrollTag 836913
#define noDisableHorizontalScrollTag 836914

@implementation UIImageView (ForScrollView)

- (void) setAlpha:(float)alpha {

if (self.superview.tag == noDisableVerticalScrollTag) {
if (alpha == 0 && self.autoresizingMask == UIViewAutoresizingFlexibleLeftMargin) {
if (self.frame.size.width < 10 && self.frame.size.height > self.frame.size.width) {
UIScrollView *sc = (UIScrollView*)self.superview;
if (sc.frame.size.height < sc.contentSize.height) {
return;
}
}
}
}

if (self.superview.tag == noDisableHorizontalScrollTag) {
if (alpha == 0 && self.autoresizingMask == UIViewAutoresizingFlexibleTopMargin) {
if (self.frame.size.height < 10 && self.frame.size.height < self.frame.size.width) {
UIScrollView *sc = (UIScrollView*)self.superview;
if (sc.frame.size.width < sc.contentSize.width) {
return;
}
}
}
}

[super setAlpha:alpha];
}
@end

If you want both scroll it’s easy to change code.

Simple EKDemo – EKEvent

Vladimir Boychentsov — Sun, 06 Nov 2011 00:28:57 +0000

Now we have controller for creating events. This controller included from 4.0 iOS SDK.

SimpleEKDemo

The application uses table views to display EKCalendar object and EKEvent objects retrieved from an EKEventStore object. It implements EKEventViewController for viewing and editing existing EKEvents, and uses EKEventEditViewController for creating new EKEvents.

My Custom UITextView with syntax highlighting

Vladimir Boychentsov — Sat, 05 Nov 2011 00:51:21 +0000

Tweeting – example of Apple

Vladimir Boychentsov — Wed, 05 Oct 2011 11:51:43 +0000

Tweeting

Small feature with UIlabel

Vladimir Boychentsov — Fri, 14 Jan 2011 22:24:44 +0000

Add framework QuartzCore

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#import

UILabel *label = [[UILabel alloc] init];
[label setTextColor:[UIColor whiteColor]];
[label setBackgroundColor:[UIColor darkGrayColor]];

[[label layer] setBorderWidth:2];
[[label layer] setCornerRadius:15];
[[label layer] setBorderColor:[UIColor whiteColor].CGColor];

[label setAlpha:0.8];
[label setTextAlignment:UITextAlignmentCenter];
[label setFrame:CGRectMake(0, 0, 220, 50)];
[label setText:@"Loading..."];
[label setCenter:window.center];
[window addSubview:label];

Result:

Sample usage UIDownloadBar

Vladimir Boychentsov — Wed, 20 Oct 2010 13:30:36 +0000

Hello

Copy UI for additiolan screen

Vladimir Boychentsov — Tue, 19 Oct 2010 23:04:49 +0000

Пример копирования объектов UI на дополнительный экран

Все очень просто, для копирования необходимо выполнить всего 2 метода.

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// copy UI
// archiving data
NSData *archivedData = [NSKeyedArchiver archivedDataWithRootObject: window];
//extract data
externalWindow = [[NSKeyedUnarchiver unarchiveObjectWithData:archivedData] retain];

Внимание: Интерфейс копируется только без картинок, если будут картинки, то получите креш. Так же скопированные объекты не синхронизированны.

Далее исходники и ролик демострирующий результат…

Source

UIImage and Memory

Vladimir Boychentsov — Thu, 10 Jun 2010 11:43:22 +0000

+[UIImage imageNamed:]
• Reads the ﬁle, uncompresses it, caches result
• Cached copy of data is kept even if the UIImage is deallocated
• Low memory condition causes cache to be purged.
• No direct control over when cache is purged.
• Use for small frequently drawn images.

+[UIImage imageWithContentsOfFile:]
• Just reads enough of ﬁle to determine if it can open the ﬁle.
• Reads and uncompresses the ﬁle each time it draws. Uses uncompressed size worth of memory only temporarily.
• Assigning a UIImage created this way to a UIImageView or as the contents of a CALayer also causes it to read and uncompress the ﬁle. The UIImageView or CALayer keep the expanded version.

Memory Usage (in MB) 8.6 MB image used with UIImageView

	imageNamed	imageWithContentsofFile
Initial	2.46	2.46
Load UIImage	11.12	2.51
Assign to UIImageView	11.09	11.09
Remove from UIImageView	11.12	2.51

Memory Usage (in MB) 8.6 MB image used with UIView subclass (stored in instance variable and drawn with drawinRect: )

	imageNamed	imageWithContentsofFile
Initial	2.73	2.73
Load UIImage	11.38	2.78
Assign to UIImageView	11.81	3.20
Remove from UIImageView	11.84	3.04

Спасибо за некоторые пояснения Андрею Копаневу :)

И вот этому документу – Robert Clair

Make gradient on iPhone/iPad

Vladimir Boychentsov — Sun, 30 May 2010 18:57:09 +0000

It’s easy! As of iPhone SDK 3.0, custom gradients can be implemented very easily, without subclassing or images, by using the new CAGradientLayer

add framework

1	#import < QuartzCore/QuartzCore.h>

so, example:

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UIView *myTabView = [[UIView alloc] initWithFrame:frame];
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = myTabView.bounds;
gradient.colors = [NSArray arrayWithObjects:
(id)[[UIColor colorWithRed:0.1 green:0.1 blue:0.1 alpha:0.8 ] CGColor]
, (id)[[UIColor colorWithRed:0.1 green:0.1 blue:0.1 alpha:0.8 ] CGColor]
, (id)[[UIColor colorWithRed:0.1 green:0.1 blue:0.1 alpha:0.8 ] CGColor]
, (id)[[UIColor blackColor] CGColor]
, (id)[[UIColor blackColor] CGColor], nil];
[myTabView.layer insertSublayer:gradient atIndex:0];
[[self.tabBarController tabBar] insertSubview:myTabView atIndex:0];
[myTabView release];

Result:

or, nice example with use Core Graphics to draw the gradient

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- (void)drawRect:(CGRect)rect
{
CGContextRef currentContext = UIGraphicsGetCurrentContext();

CGGradientRef glossGradient;
CGColorSpaceRef rgbColorspace;
size_t num_locations = 2;
CGFloat locations[2] = { 0.0, 1.0 };
CGFloat components[8] = { 1.0, 1.0, 1.0, 0.35, // Start color
1.0, 1.0, 1.0, 0.06 }; // End color

rgbColorspace = CGColorSpaceCreateDeviceRGB();
glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);

CGRect currentBounds = self.bounds;
CGPoint topCenter = CGPointMake(CGRectGetMidX(currentBounds), 0.0f);
CGPoint midCenter = CGPointMake(CGRectGetMidX(currentBounds), CGRectGetMidY(currentBounds));
CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, midCenter, 0);

CGGradientRelease(glossGradient);
CGColorSpaceRelease(rgbColorspace);
}

Many documentations

resource

Streatch image with stretchableImageWithLeftCapWidth: topCapHeight:

Vladimir Boychentsov — Wed, 10 Mar 2010 14:43:38 +0000

Sample

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+ (UIImage*)greenBubble
{
if (sGreenBubble == nil) {
UIImage *i = [UIImage imageNamed:@"Balloon_1.png"];
sGreenBubble = [[i stretchableImageWithLeftCapWidth:15 topCapHeight:13] retain];
}
return sGreenBubble;
}

+ (UIImage*)grayBubble
{
if (sGrayBubble == nil) {
UIImage *i = [UIImage imageNamed:@"Balloon_2.png"];
sGrayBubble = [[i stretchableImageWithLeftCapWidth:21 topCapHeight:13] retain];
}
return sGrayBubble;
}

Results:

or

испоьзовал 2 картинки