What is basically an umbrella header? What is its use? I got a warning as shown below. What does this mean?
<module-includes>:1:1: warning: umbrella header for module 'XCTest' does not include header 'XCTextCase+AsynchronousTesting.h' [-Wincomplete-umbrella] #import "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/Library/Frameworks/XCTest.framework/Headers/XCTest.h"
umbrella header - iOS framework or library on Objective-C or Swift can have a header file that contains references to all the other headers in that project. When you create a framework target Xcode will automatically generate <targer_name.h> file.
The module map language describes the mapping from header files to the logical structure of modules. To enable support for using a library as a module, one must write a module. modulemap file for that library.
Alternatively, you can create a bridging header yourself by choosing File > New > File > [operating system] > Source > Header File. Edit the bridging header to expose your Objective-C code to your Swift code: In your Objective-C bridging header, import every Objective-C header you want to expose to Swift.
The umbrella header is the 'master' header file for a framework. Its use is that you can write
#import <UIKit/UIKit.h>
instead of
#import <UIKit/UIViewController.h> #import <UIKit/UILabel.h> #import <UIKit/UIButton.h> #import <UIKit/UIDatePicker.h>
and so on.
For me, <XCTest/XCTestCase+AsynchronousTesting.h>
is included in <XCTest/XCTest.h>
. Maybe it is not for you? In that case, add the
#import <XCTest/XCTestCase+AsynchronousTesting.h>
manually.
umbrella header
- iOS framework
or library
on Objective-C
or Swift
can have a header file that contains references to all the other headers in that project.
When you create a framework target Xcode will automatically generate <targer_name.h>
file. It should has the same name as PRODUCT_NAME
For example <umbrella_name.h>
looks like
#import "header_1.h" #import "header_2.h"
or:
#import <Foundation/Foundation.h> #import <UIKit/UIKit.h> //! Project version number for SomeModule. FOUNDATION_EXPORT double SomeModuleVersionNumber; //! Project version string for SomeModule. FOUNDATION_EXPORT const unsigned char SomeModuleVersionString[]; // In this header, you should import all the public headers of your framework using statements like #import <SomeModule/PublicHeader.h>
As a result you can use the next syntax
#import <umbrella_name.h>
instead of
#import <header_1.h> #import <header_2.h>
On practice when you create a Framework
on Objective-C
[Example] or Swift
[Example] this file will be created automatically with <product_name>
Using
1.umbrella header
is required by [.modulemap
] structure to use module(expose Objective-C headers) for Objective-C or Swift
2.umbrella header
can be just used by Objective-C consumer for connivance
3.umbrella header
helps to import every Objective-C header into Swift module that is why you can just skip import
Swift sees every header you expose publicly in your umbrella header. The contents of the Objective-C files in that framework are automatically available from any Swift file within that framework target, with no import statements. Use classes and other declarations from your Objective-C code with the same Swift syntax you use for system classes.
Importing Objective-C
into Swift
within a Framework Target
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