No memory leak, still app is out of memory?

In iPhone/iPad app I have came across many situations where there was absolutely no memory leak, but app was crashing after some time due to out of memory. The reason could be many. Your application may be huge and you are using many resources/data which you are not using but still not releasing them.

Most of the time this happens with images. Below line could be fetal.


UIImage *img = [UIImage imageNamed:@"someimage.png"];

The method imageNamed from UIImage caches image data so that it could load it faster next time. This is great for smaller images, but shouldn't be used for heavy images. Instead use imageWithContentsOfFile method.

What happens with imageNamed method is that, if your app loads n number of images then all those images will be cached and will never be released until the app is quit. You may not see any memory leak using static-analyzer or in instruments. If you see the allocation in instruments you may see steady increase in the allocated memory which is never used.

Update to XCode 4.2 in Mac OSX Lion

Today i faced a strange problem while updating Xcode from 4.1 to 4.2 using mac app store in lion. Mac store was giving me a option to update Xcode to 4.2. So i pressed update button. It was written 1.6GB. But to my surprise it downloaded around 3.4 GB (i think it downloaded reference library). When download got finished i clicked on Xcode icon in launchpad to install. But after installing Xcode was still 4.1. Many might have faced this problem. Finally i was able to install Xcode. you can follow the steps given below. Correct me if iam wrong here or if it didn't work for you

1. Un-Install XCode by command  sudo /Developer/Library/uninstall-devtools --mode=all
2. Restart your Mac
3. Delete the file XCode Install.app from your mac. It could be in your Applications directory or in Downloads or wherever it is. Delete from trash also. (Here Xcode Install.app is the previous installation file which you used to install XCode 4.1 in lion). This is very important step.
4. Now go to mac store, search for XCode and install

I am yet to explore Xcode 4.2. Happy coding
Thank you

Keep Passwords Safe

     Today we live in two worlds. One is real world and other is virtual (internet/cyber/computer) world. Even-though both worlds exists in different space, they are connected, and we can say they are interconnected.
    To make private belongings of a person safe in internet world PASSWORD is the key factor. For email, twitter, Facebook, bank account etc password is the protector. But most people do mistake here. Everyone has difficulty in remembering passwords. So they keep same password for all accounts. Another reason for keeping same password is, most sites use email-id as the login or username. So people think we have to give real password of their email id while creating the account. This we can see practically see in Facebook accounts. While creating Facebook account email-id is taken as login or user name, then it asks for password. People simply type same password of their email id here.

The thing i want to put forward is

1. Don't use same password for all your accounts
2. If email-id is asked as login name while creating a account, then don't use the same password of that email id for new account.
3. Don't use option of remember password in web-browsers (Firefox, chrome)
4. Use some uppercase letters and numbers in password to make it hard to guess
5. If you are using public computer use Private browsing option in Firefox and new incognito window in chrome

Safe browsing

Pinch Zoom UITableView

We can give pinch zoom feature to UITableView using UIPinchGesture. Below is the subclass of UITableView which can be directly used to enable pinch zoom capability for your table view. Just you need to change the class of UITable in nib as shown below.

Just you need to add "PinchZoomTableView.h" and "PinchZoomTableView.m" to your project. Then change the class from UITableView to PinchZoomTableView in the nib file where UITable is used. You can download the sample project from https://github.com/sachithkadamba/PinchZoomUITableView.  Or You can copy paste PinchZoomTableView.h and PinchZoomTableView.m from below.

	//PinchZoomTableView.h
	//Created by Sachith on 14/01/11.
	/*Copyright 2011 Sachith Kadamba <sachithkadamba@gmail.com>
	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU  Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or
	(at your option) any later version.
	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.
	You should have received a copy of the GNU Lesser General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
	MA 02110-1301, USA.*/
	// For any Queries or suggestion contact me :sachithkadamba@gmail.com
	/*
	This works both for iPhone and iPad in all orientaions.
	For any bugs or improvements feel free to contact me.
	*/
	#import <UIKit/UIKit.h>
	@interface PinchZoomTableView : UITableView <UIGestureRecognizerDelegate>{
	CGRect originalFrame;
	CGFloat screenWidth;
	CGFloat screenHeight;
	CGFloat deltaY;
	}
	@property (nonatomic, readwrite) CGRect originalFrame;
	@property (nonatomic, readwrite) CGFloat screenWidth;
	@property (nonatomic, readwrite) CGFloat screenHeight;
	@property (nonatomic, readwrite) CGFloat deltaY;
	- (void) resetTable;
	- (void) addGesture;
	@end

view raw PinchZoomTableView.h hosted with ❤ by GitHub

	//PinchZoomTableView.m
	//Created by Sachith on 14/01/11.
	Copyright 2011 Sachith Kadamba <sachithkadamba@gmail.com>
	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU  Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or
	(at your option) any later version.
	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.
	You should have received a copy of the GNU Lesser General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
	MA 02110-1301, USA.*/
	// For any Queries or suggestion contact me :sachithkadamba@gmail.com
	#import "PinchZoomTableView.h"
	#import <QuartzCore/QuartzCore.h>
	@implementation PinchZoomTableView
	@synthesize originalFrame;
	@synthesize screenWidth;
	@synthesize screenHeight;
	@synthesize deltaY;
	-(void)awakeFromNib {
	[self addGesture];
	CGRect wh = [[UIScreen mainScreen]bounds];
	screenWidth = wh.size.width;
	screenHeight = wh.size.height;
	/*
	For iPad i found deltaY as 120.. you can change this for your requirement
	*/
	if(screenWidth > 1000) {
	deltaY = 120;
	}
	else {
	deltaY = 50;
	}
	}
	- (void)addGesture {
	self.clipsToBounds = YES;
	UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(scalePiece:)];
	[pinchGesture setDelegate:self];
	[self addGestureRecognizer:pinchGesture];
	[pinchGesture release];
	}
	- (void)adjustAnchorPointForGestureRecognizer:(UIGestureRecognizer *)gestureRecognizer {
	if (gestureRecognizer.state == UIGestureRecognizerStateBegan) {
	UIView *piece = gestureRecognizer.view;
	originalFrame.size.height = self.frame.size.height;
	self.originalFrame = self.frame;
	CGPoint locationInView = [gestureRecognizer locationInView:nil];
	CGPoint locationInSuperview = [gestureRecognizer locationInView:piece.superview];
	UIInterfaceOrientation orientaion = [[UIDevice currentDevice]orientation];
	/*some times Device gives unknown orientaion
	If Device orientaion is unkown check orientaion of status bar
	*/
	if( orientaion != UIInterfaceOrientationPortrait && orientaion != UIInterfaceOrientationPortraitUpsideDown &&orientaion != UIInterfaceOrientationLandscapeLeft && orientaion != UIInterfaceOrientationLandscapeRight) {
	orientaion = [[UIApplication sharedApplication] statusBarOrientation];
	}
	if( orientaion == UIInterfaceOrientationPortrait ) {
	}
	else if ( orientaion == UIInterfaceOrientationPortraitUpsideDown ) {
	locationInView.x = screenWidth - locationInView.x;
	locationInView.y = (screenHeight -20) - locationInView.y;
	}
	else if ( orientaion == UIInterfaceOrientationLandscapeLeft ) {
	float x = screenHeight - locationInView.y;
	float y = locationInView.x;
	locationInView.x = x;
	locationInView.y = y;
	}
	else if ( orientaion == UIInterfaceOrientationLandscapeRight ) {
	float y = locationInView.y;
	float x = screenWidth - locationInView.x;
	locationInView.x = y;
	locationInView.y = x;
	}
	piece.layer.anchorPoint = CGPointMake(locationInView.x / piece.bounds.size.width, (locationInView.y -deltaY) / piece.bounds.size.height);
	piece.center = locationInSuperview;
	}
	else if(gestureRecognizer.state == UIGestureRecognizerStateEnded) {
	[self resetTable];
	}
	}
	- (void)resetTable {
	[UIView beginAnimations:nil context:nil];
	[self setTransform:CGAffineTransformIdentity];
	self.frame = originalFrame;
	[UIView commitAnimations];
	}
	- (void)scalePiece:(UIPinchGestureRecognizer *)gestureRecognizer {
	[self adjustAnchorPointForGestureRecognizer:gestureRecognizer];
	if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {
	[gestureRecognizer view].transform = CGAffineTransformScale([[gestureRecognizer view] transform], [gestureRecognizer scale], [gestureRecognizer scale]);
	[gestureRecognizer setScale:1];
	}
	}
	- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
	return YES;
	}
	-(void)dealloc {
	[super dealloc];
	}
	@end

view raw PinchZoomTableView.m hosted with ❤ by GitHub

Please leave comments if this post helped you and also please share the code if you have fixed any bug or improved this code so that it helps others.

Privacy Policy

This blog does not share personal information with third parties nor do we store any information about your visit to this blog other than to analyze and optimize your content and reading experience through the use of cookies.

You can turn off the use of cookies at anytime by changing your specific browser settings.

We are not responsible for republished content from this blog on other blogs or websites without our permission.

This privacy policy is subject to change without notice. If you have any questions feel free to contact me directly here sachk1988@gmail.com