When developing iOS applications with Xcode, it’s essential to understand the difference between “Target Dependencies” and “Link Binary with Libraries.” These two options found in the Build Phases settings of a target play vital roles in defining how your app interacts with external code. In this article, we’ll discuss what these options do and how they are different.

Understanding Targets

Before we delve into the differences, let’s first understand what a ‘Target’ is in Xcode. A target specifies a set of build configurations which define how to build a product in Xcode. It could be an app, a framework, or a unit test bundle. Each target contains information about how to build the product, including build settings, build phases, and the product’s dependencies.

Target Dependencies

Target Dependencies is an option in the Build Phases settings of a target. This is where you specify the targets that must be built before the current target. For instance, if your app target depends on a custom framework target you have defined in the same project, then that framework is a target dependency.

By adding the framework to the Target Dependencies, you’re instructing Xcode to build that framework before building the app target. This ensures that the most recent build of the framework is available to the app when it is being built.

The “Link Binary with Libraries” build phase in Xcode is where you establish connections between your target and the libraries or frameworks it requires. This includes several types of libraries and frameworks:

  • System frameworks or libraries: These are pre-existing libraries provided by Apple, such as UIKit, CoreData, MapKit, etc., that you may utilize in your project. They offer a broad array of pre-built functionalities that can expedite your app development process.
  • Third-party libraries: These could be open-source libraries or proprietary code made available by other developers or companies for use in your project. They are typically downloaded and integrated into your project to provide specific functionalities that you don’t want to build from scratch.
  • Libraries or frameworks defined in your project: These are custom frameworks or libraries you’ve created as part of your project to modularize your code and make it more reusable.

When you add a framework or a library to the “Link Binary with Libraries” phase, you’re telling Xcode that your target needs to access and use code or resources from that particular framework or library.

During the linking process, Xcode looks at the symbols (functions, methods, variables, classes, etc.) used in your code that are defined in the linked framework or library. It then connects these symbols, so, at runtime, your app knows exactly where to find and execute the correct pieces of code.

Without this linking process, your app wouldn’t know where to find the implementation of the used symbols, leading to undefined symbols errors.

This process of resolution is handled by the linker, a tool that takes one or more objects generated by a compiler and combines them into a single executable program. It resolves references to external symbols, assigns final addresses to functions and variables, and revises code and data to reflect new addresses (a process known as relocation).

Therefore, the “Link Binary with Libraries” phase is crucial to ensuring that your application has access to the necessary code and resources, and can correctly execute them at runtime.

The Differences

While both options involve how your app interacts with other targets, the difference lies in their purpose:

  • Target Dependencies is about building order. It ensures that the dependent targets are built first before the current target. However, it does not link the dependent target’s binary with your target.

  • Link Binary with Libraries is about linking binaries. It’s responsible for linking the necessary frameworks or libraries’ binaries with your target. However, it does not ensure the order of building targets.

In a typical scenario where your app uses a custom framework defined in the same project, you would add the framework in both sections—Target Dependencies and Link Binary with Libraries. This ensures that the framework is built before your app and its binary is linked to it.


Knowing how to properly use “Target Dependencies” and “Link Binary with Libraries” is fundamental for managing complex projects in Xcode. While the former ensures the correct build order, the latter guarantees the appropriate linking of the binaries. Understanding these differences will help you create more efficient and reliable build settings in your iOS projects.