Ios – Why the UISearchBar`s frame is changed by the UISearchDisplayController

iosuisearchbaruisearchbardelegateuisearchbardisplaycontroluisearchdisplaycontroller

I write UISearchBar in my TopBar.m like this:

_tempSearchBar =[[UISearchBar alloc]initWithFrame:CGRectMake(44, 0, 320 - 44, 43)];
_tempSearchBar.barStyle=UIBarStyleDefault;
_tempSearchBar.placeholder=@"搜索";
[self addSubview:_tempSearchBar];

the result is like this, it is right.
enter image description here

and then I write UISearchDisplayController in another class like this:

_topBar.tempSearchBar.delegate = self;    
_searchDisplayController = [[UISearchDisplayController alloc] initWithSearchBar:_topBar.tempSearchBar contentsController:self];
[_searchDisplayController setDelegate:self];
[_searchDisplayController setSearchResultsDataSource:self];

the UISearchBarDelegate is like this:

#pragma mark -
#pragma mark UISearchBarDelegate
- (void)searchBarTextDidBeginEditing:(UISearchBar *)searchBar
{
    [_searchDisplayController setActive:YES animated:YES];
}

when I click the UISearchBar , it show like this , the searchBar`s frame is changed.why?
enter image description here

when I cancel the UISearchDisplayController it is like this :
enter image description here

why the frame is changed? The width is changed from 320-44 to 320 by the UISearchDisplayController?
thanks.

Best Answer

UISearchDisplayController expands the search bar to the width of its superview. The simplest solution that I have found is to place the search bar inside another UIView that has the width I am looking for.

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Ios – What’s the difference between the atomic and nonatomic attributes

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Assuming that you are @synthesizing the method implementations, atomic vs. non-atomic changes the generated code. If you are writing your own setter/getters, atomic/nonatomic/retain/assign/copy are merely advisory. (Note: @synthesize is now the default behavior in recent versions of LLVM. There is also no need to declare instance variables; they will be synthesized automatically, too, and will have an _ prepended to their name to prevent accidental direct access).

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In nonatomic, no such guarantees are made. Thus, nonatomic is considerably faster than "atomic".

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Ensuring data integrity -- one of the primary challenges of multi-threaded programming -- is achieved by other means.

Adding to this:

atomicity of a single property also cannot guarantee thread safety when multiple dependent properties are in play.

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 @property(atomic, copy) NSString *firstName;
 @property(atomic, copy) NSString *lastName;
 @property(readonly, atomic, copy) NSString *fullName;

In this case, thread A could be renaming the object by calling setFirstName: and then calling setLastName:. In the meantime, thread B may call fullName in between thread A's two calls and will receive the new first name coupled with the old last name.

To address this, you need a transactional model. I.e. some other kind of synchronization and/or exclusion that allows one to exclude access to fullName while the dependent properties are being updated.

Ios – Styling the cancel button in a UISearchBar

You can use UIAppearance to style the cancel button without iterating subviews of the UISearchBar, but the UIButton header does not currently have any methods annotated with UI_APPEARANCE_SELECTOR.

EDIT: Drill down the subviews till you get that cancel button

But this usually returns nil until searchBar.setShowsCancelButton(true, animated: true) is called.

extension UISearchBar {

var cancelButton : UIButton? {
    if let view = self.subviews.first {
        for subView in view.subviews {
            if let cancelButton = subView as? UIButton {
                return cancelButton
            }
        }
    }
    return nil
}
}

Best Answer

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