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Warning: Reference to captured var 'hashBag' in concurrently-executing code
I get many warnings like this when I build an old project. I asked AI chatbot which gave me several solutions, the recommended one is: var hashBag = [String: Int]() func updateHashBag() async { var tempHashBag = hashBag // make copy await withTaskGroup(of: Void.self) { group in group.addTask { tempHashBag["key1"] = 1 } group.addTask { tempHashBag["key2"] = 2 } } hashBag = tempHashBag // copy back? } My understanding is that in the task group, the concurrency engine ensures synchronized modifications on the temp copy in multiple tasks. I should not worry about this. My question is about performance. What if I want to put a lot of data into the bag? Does the compiler do some kind of magics to optimize low level memory allocations? For example, the temp copy actually is not a real copy, it is a special reference to the original hash bag; it is only grammar glue that I am modifying the copy.
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207
Apr ’25
Piece of code in Playground that reliably crashes lldb server
Dare anyone try the following code in any Playground: // Define a model that conforms to Codable struct User: Codable { var name: String var age: Int var email: String? } // JSON data (as a string for demonstration) let jsonString = """ { "name": "John Doe", "age": 30, "email": "john@example.com" } """ // Convert the JSON string to Data if let jsonData = jsonString.data(using: .utf8) { do { // Parse the JSON data into the User model let user = try JSONDecoder().decode(User.self, from: jsonData) print("Name: \(user.name), Age: \(user.age), Email: \(user.email ?? "N/A")") } catch { print("Error decoding JSON: \(error)") } } I tested with Xcode 16.2 and latest 16.3, it reliably crashes the lldb server!
6
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328
Apr ’25
How include dSYM when I build my Framework project?
This question is related to this post (of mine). It seems default build settings do not include dSYM files needed when uploading embedding app package. But now Xcode issues new warnings about this. Now the question - how do I tell Xcode to create dSYM files for me, say when I build My.Framework? I asked AI chatbot which tells me that for release build I need to : set "Debug Information Format" to DWARF set "Strip Debug Symbols During Copy" to off I have item 1 turned on (which I believe is the default). But item 2 is on, maybe that's the reason I do not have dSYM files in final built My.Framework. Should I turn "Strip Debug Symbols During Copy" off?
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196
Apr ’25
Xcode Documentation window eats up much CPU time
After upgrading to Xcode 16.3, whenever I open the Documentation window, Xcode started CPU hungry mode, forever. Does anyone else have the same experience as me? Is there any known remedy so far?
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2
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155
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Apr ’25
Warning: Reference to captured var 'hashBag' in concurrently-executing code
I get many warnings like this when I build an old project. I asked AI chatbot which gave me several solutions, the recommended one is: var hashBag = [String: Int]() func updateHashBag() async { var tempHashBag = hashBag // make copy await withTaskGroup(of: Void.self) { group in group.addTask { tempHashBag["key1"] = 1 } group.addTask { tempHashBag["key2"] = 2 } } hashBag = tempHashBag // copy back? } My understanding is that in the task group, the concurrency engine ensures synchronized modifications on the temp copy in multiple tasks. I should not worry about this. My question is about performance. What if I want to put a lot of data into the bag? Does the compiler do some kind of magics to optimize low level memory allocations? For example, the temp copy actually is not a real copy, it is a special reference to the original hash bag; it is only grammar glue that I am modifying the copy.
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4
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207
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Apr ’25
Piece of code in Playground that reliably crashes lldb server
Dare anyone try the following code in any Playground: // Define a model that conforms to Codable struct User: Codable { var name: String var age: Int var email: String? } // JSON data (as a string for demonstration) let jsonString = """ { "name": "John Doe", "age": 30, "email": "john@example.com" } """ // Convert the JSON string to Data if let jsonData = jsonString.data(using: .utf8) { do { // Parse the JSON data into the User model let user = try JSONDecoder().decode(User.self, from: jsonData) print("Name: \(user.name), Age: \(user.age), Email: \(user.email ?? "N/A")") } catch { print("Error decoding JSON: \(error)") } } I tested with Xcode 16.2 and latest 16.3, it reliably crashes the lldb server!
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6
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1
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328
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Apr ’25
How include dSYM when I build my Framework project?
This question is related to this post (of mine). It seems default build settings do not include dSYM files needed when uploading embedding app package. But now Xcode issues new warnings about this. Now the question - how do I tell Xcode to create dSYM files for me, say when I build My.Framework? I asked AI chatbot which tells me that for release build I need to : set "Debug Information Format" to DWARF set "Strip Debug Symbols During Copy" to off I have item 1 turned on (which I believe is the default). But item 2 is on, maybe that's the reason I do not have dSYM files in final built My.Framework. Should I turn "Strip Debug Symbols During Copy" off?
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3
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0
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196
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Apr ’25
App upload warnings (never seen before)
I don't get any idea why I am getting the following warnings when I tried to upload one of my apps:
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3
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159
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Apr ’25
Swift project build process is extremely slow after upgrading to 16.3
For an initial launch of Xcode, the GatherProvisioningInputs usually takes 60 seconds for a simple project. Subsequent build is fast though. But the build process seems got stuck at VeryModule of the MyFramework target, which usually takes 15 seconds.
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2
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1
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135
Activity
May ’25
Does Xcode 26 only run on the new macOS 26?
I currently do not want to upgrade to macOS 26, but I still want to install the latest Xcode. Is it required to install macOS 26 if I were to get Xcode 26?
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2
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317
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Sep ’25