iOS/Xcode 2018：发布版禁用NSLog仍需手动创建pch文件吗？

Short answer: No, you shouldn't—the old pch-based method is outdated now that Xcode doesn’t auto-generate pch files, and there are cleaner, more efficient alternatives available today.

Why the PCH Approach Is Not Ideal Anymore #

• Xcode hasn’t auto-created pch files by default for years, and manually setting one up adds unnecessary overhead with little benefit.
• Pch files force their contents to be included in every source file in your project, which can slow down compile times—especially noticeable in larger apps.
• It’s a rigid solution that ties your logging setup to a single global file, making it harder to adjust or extend your logging behavior later.

Better Alternatives #

1. Use a Custom Header with Compilation Macros (Objective-C/Swift)

This is the most common and flexible approach today:

• Objective-C:

  1. Create a shared header file (e.g., LoggingUtils.h) in your project.
  2. Add this code to it:

     #ifdef DEBUG
     #define NSLog(...) NSLog(@"[%@:%d] %@", [[NSString stringWithUTF8String:__FILE__] lastPathComponent], __LINE__, [NSString stringWithFormat:__VA_ARGS__])
     #else
     #define NSLog(...)
     #endif
     

  3. Import this header in any file where you use NSLog, or add it to your project’s Header Search Paths and enable "Always Search User Paths" if you want it available globally without manual imports.

• Swift:
  Swift doesn’t support macros, but you can use compile-time conditionals to create a debug-only log function:

  #if DEBUG
  func debugLog(_ message: String, file: String = #file, function: String = #function, line: Int = #line) {
      let fileName = URL(fileURLWithPath: file).lastPathComponent
      print("[\(fileName):\(line)] \(function) → \(message)")
  }
  #else
  func debugLog(_ message: String, file: String = #file, function: String = #function, line: Int = #line) {}
  #endif
  

  Then use debugLog("Your debug message here") instead of print for logs that only appear in debug builds.

2. Wrap Logs Directly with Debug Flags

Xcode already defines a DEBUG macro by default for debug builds (check this in Build Settings > Preprocessor Macros under the Debug configuration). You can use this directly if you only need to disable specific logs:

#ifdef DEBUG
NSLog("This will only show up in debug builds");
#endif

This is less convenient than the macro approach, though, since you have to wrap every log statement individually.

When Would You Still Use PCH? #

Honestly, there’s almost no good reason to stick with the pch method today. Even if you’re working on an older project that already has a pch file, migrating to the custom header approach is worth it for better maintainability and faster builds.

内容的提问来源于stack exchange，提问作者user6631314