Understanding the Issues with ZXING on iOS 7

Introduction to ZXING and iOS 7

ZXING is a popular open-source barcode scanning library used in many applications. The library provides a wide range of features, including support for multiple barcode formats, image processing, and device camera access. However, when it comes to integrating ZXING with iOS 7, there are some common issues that developers may encounter.

One such issue was reported in a Stack Overflow post, where the user encountered an error while trying to build their application using the Apple LLVM 5.0 compiler. The error message indicated that there were undefined symbols for the architecture i386.

Understanding the Error Message

To understand the error message, let’s break it down:

• Undefined symbols is a compiler error that occurs when the compiler cannot find a definition for a symbol (variable or function) in the code.
• for architecture i386 refers to the specific architecture of the CPU that the error is occurring on. In this case, it’s an i386-based architecture.

The error message mentions std::string::compare(std::string const& const) as the referenced symbol. This is a function from the C++ Standard Library that compares two strings for equality. However, the compiler is unable to find a definition for this function.

The Problem with libstdc++ and libc++

When building an application on iOS 7, there are two main libraries involved: libc++ and libstdc++. These libraries provide the C++ standard library functionality that developers rely on.

• libstdc++ is a dynamic library that provides the complete C++ Standard Library. It’s used by most modern applications.
• libc++ is a static library that provides the core parts of the C++ Standard Library, but excludes some features and headers to make it smaller in size.

The error message suggests that the ZXING library was built with libstdc++, which includes the dynamic linking. However, when building on iOS 7, the compiler defaults to using libc++ instead of libstdc++.

The Solution: Changing the Standard Library Setting

To resolve this issue, developers can change the standard library setting in their project to use libstdc++ instead of libc++. Here’s how:

1. Open your Xcode project and navigate to the Build Settings.
2. Search for Standard Library and select libstdc++.cpp.
3. Clean and rebuild the project.

Alternatively, developers can look for a version of the ZXING library that’s built with libc++. This will ensure compatibility with iOS 7.

Additional Considerations

When working with iOS 7 and ZXING, there are some additional considerations to keep in mind:

• Xcode versions: Ensure you’re using Xcode 4.6 or later for iOS 7 support.
• Compiler settings: Verify that your compiler settings match the requirements of the ZXING library.
• Project structure: Make sure your project structure is correct, with the necessary dependencies and frameworks.

By understanding the issues with ZXING on iOS 7 and following these steps, developers can resolve common errors and ensure successful integration of the barcode scanning library in their applications.

Best Practices for Working with ZXING

When working with ZXING, here are some best practices to keep in mind:

• Use the latest version: Ensure you’re using the latest version of ZXING, as it may include bug fixes and performance improvements.
• Follow the documentation: Read the official documentation for the ZXING library to understand its features and usage.
• Test thoroughly: Thoroughly test your application to ensure that it works correctly with the ZXING library.

By following these best practices and understanding the common issues with ZXING on iOS 7, developers can create reliable and efficient barcode scanning applications.

Last modified on 2023-10-15