Category: iOS

This is how you determine, if device has a screen size of iPhone 5 if you develop an app for iPhones only.

#define IS_WIDESCREEN [[UIScreen mainScreen] bounds].size.height >= 568

Here is much more complex way to determine this.

double delayInSeconds = 2.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
    <#code to be executed on the main queue after delay#>
});

Apple GCD Reference

<br />
playImage.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin;<br />
[cell.contentView addSubview:playImage];<br />
playImage.center = CGPointMake(cell.contentView.bounds.size.width/2,cell.contentView.bounds.size.height/2);<br />

I wanted to show an alertView to a user with a textField. This is what was achieved:

First, I tried to use Block Alerts and ActionSheets, but I failed. Then I discovered, that there is a standart way to do this. There are some UIAlertView styles available beyond a default style: UIAlertViewStyleLoginAndPasswordInput, UIAlertViewStylePlainTextInput and UIAlertViewStyleSecureTextInput. In this case we will use the second one. Works on iOS 5 and later:

<br />
UIAlertView *av = [[UIAlertView alloc] initWithTitle:LS(@”Document file name”) message:@”Please enter document file name.” delegate:self cancelButtonTitle:LS(@”Cancel”) otherButtonTitles:LS(@”Save”), nil];<br />
av.alertViewStyle = UIAlertViewStylePlainTextInput;<br />
[av textFieldAtIndex:0].delegate = self;<br />
[av textFieldAtIndex:0].text = self.mcAttachDisplayed.fileName;<br />
[av show];<br />

Then, you should define two protocols UITextFieldDelegate, UIAlertViewDelegate.
And implement methods:

<br />
– (BOOL)textFieldShouldReturn:(UITextField *)textField<br />
{<br />
    [textField resignFirstResponder];<br />
    return YES;<br />
}</p>
<p>– (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex<br />
{<br />
    NSLog(@”Button index clicked:%d”, buttonIndex);</p>
<p>    switch (buttonIndex) {<br />
        case 0:<br />
            break;<br />
        case 1:{<br />
            NSLog(@”Save Clicked”);<br />
            UITextField *textField = [alertView textFieldAtIndex:0];<br />
            NSString *text = textField.text;</p>
<p>            break;<br />
        }<br />
        default:<br />
            break;<br />
    }<br />
}<br />

References:
StackOverFlow question

Recently I was guessing, how to work with flags in MailCore, where a flag is NSUInteger. I got answer from MailCore Librelist.

The flags are stored as bitwise operations. If you want to check to see if a message is deleted, for example, you can do the following bitwise operation:

if (coreMessage.flags & CTFlagDeleted) {
            NSLog(@"Message has been deleted.");
}

More explanation from me.

This is a list of Flags:

/** List of Message Flags **/

#define CTFlagNew		MAIL_FLAG_NEW 
#define CTFlagSeen		MAIL_FLAG_SEEN
#define CTFlagFlagged		MAIL_FLAG_FLAGGED
#define CTFlagDeleted		MAIL_FLAG_DELETED
#define CTFlagAnswered		MAIL_FLAG_ANSWERED
#define CTFlagForwarded		MAIL_FLAG_FORWARDED
#define CTFlagCancelled 	MAIL_FLAG_CANCELLED

Meaning of the right column here is:

enum {
  MAIL_FLAG_NEW       = 1 << 0,
  MAIL_FLAG_SEEN      = 1 << 1,
  MAIL_FLAG_FLAGGED   = 1 << 2,
  MAIL_FLAG_DELETED   = 1 << 3,
  MAIL_FLAG_ANSWERED  = 1 << 4,
  MAIL_FLAG_FORWARDED = 1 << 5,
  MAIL_FLAG_CANCELLED = 1 << 6
};

Let's use a Decimal to Binary converter.

For instance, 34 is 100010. We see, that 2nd and 6th bits are not null. So Flags are CTFlagSeen and CTFlagForwarded. Since CTFlagSeen = MAIL_FLAG_SEEN = 1 << 1 in binary. It means, that we should shift by 1 symbol and compare 2nd symbol in 100010. It is 1, or YES. The same is for CTFlagForwarded which is a shift by 6. If flags = 50, then binary is 110010. Flags are CTFlagSeen, CTFlagAnswered, CTFlagForwarded. Let's now assume, that we want to remove CTFlagSeen flag. What should we do? If we do this: flags = flags^CTFlagSeen we will get this in bit level: (110010)^(1<<1)=(110000), so the flag will be removed. If there was no flag, it will be installed, when we use XOR operator, represented by ^ symbol. If 18, then 10010. Flags are CTFlagSeen (10) and CTFlagAnswered(101).

The key moment here is that you should change backBarButtonItem before pushing your view controller, where you expect to change back button title. Change only the title of item doesn’t work, the whole button should be replaced.

<br />
UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:LS(@”All”) style:UIBarButtonItemStyleBordered target:nil action:nil];<br />
    self.navigationItem.backBarButtonItem = backButton;<br />
    [self.navigationController pushViewController:messageViewController animated:YES];<br />

To simulate 3G/2G Internet in iOS use Network Link Conditioner. To get it:

• Open XCode menu.
• Click Open Developer Tool
• More Developer Tools… or go directly here
• Download and install Hardware IO Tools for Xcode

Can be used to filter data under search bar. Personally I have developed it for this purpose.

Case Insensitive Method to Find a String in Another String in iOS:

<br />
– (BOOL)findString:(NSString*)searchString inString:(NSString*)bigString<br />
{<br />
    if ([bigString length]==0) {<br />
        return NO;<br />
    }</p>
<p>    if (!([bigString rangeOfString:searchString options:NSCaseInsensitiveSearch].location == NSNotFound)) {<br />
        return YES;<br />
    }</p>
<p>    return NO;<br />
}<br />

This post is not a full tutorial of how to implement this. It is just my experience description. Probably, you have the same problem with custom cells, as I had. There are a lot of tutorials, search them in Google. Another nice tutorial.

I had highly customized cells, but couldn’t understand, why do they mess up, when search starts and self.searchDisplayController.searchResultsTableView is displayed with regular cell, but not customized cells. I tried to find solution for about 2-3 hours, then I decided to make exactly the same, as others did for using custom cells. I solved the problem, that was in the absence of two delegate properties in my code. This is the correct version, of how you should initialize your UISearchBar and UISearchDisplayController (if you are doing it programmatically).

Code for ViewDidLoad method:

// Search bar
searchBar = [[UISearchBar alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
searchBar.delegate = self;
searchBar.tintColor = cell_end_color;
self.tableView.tableHeaderView = searchBar;
    
searchDisplayController = [[UISearchDisplayController alloc] initWithSearchBar:searchBar contentsController:self];
searchDisplayController.delegate = self;
searchDisplayController.searchResultsDataSource = self;
searchDisplayController.searchResultsDelegate = self;

The other parts are pretty analogous to the usual search bar usage with regular cells. For instance, look at Apple’s source code on this topic.

What is interesting, this works fine on iPad too even thought the frame is 320 px here.

References:
UISearchBar Class reference

UISearchDisplayController Class Reference