打印大量文本时，Xcode 10控制台日志很慢

Question

我注意到在Xcode 10中打印大量文本时控制台日志的性能显着下降。例如，打印收集服务器数据时会发生这种情况。有没有关于此的已知解决方案或信息？

Answer 1

迅速：

请参阅：Xcode takes long time to print debug results.

public func PrintLogs(_ message: Any, file: String = #file, function: String = #function, line: Int = #line) {
    #if DEBUG
    let className = file.components(separatedBy: "/").last ?? ""
    let classNameArr = className.components(separatedBy: ".")
    NSLog("\n\n--> Class Name:  \(classNameArr[0]) \n--> Function Name: \(function) \n--> Line: \(line)")
    print("--> Log Message: \(message)")
    #endif
}

用法：调用PrintLogs（“Hello”）而不是print（“Hello”）

样本输出：

--> Class Name:  HomeViewController 
--> Function Name: logTest() 
--> Line: 81
--> Log Message: Hello

Answer 2

我在使用print命令的Swift中遇到了同样的问题，但前提是附加了调试器。

我通过检查调试器是否附加然后使用NSLog而不是print来解决它。

要检查您的应用是否在调试器模式下运行，请参阅此处：Detect if Swift app is being run from Xcode

考虑到使用Xcode 8 + iOS 10及更高版本的日志条目被截断，请参见此处：NSLog on devices in iOS 10 / Xcode 8 seems to truncate? Why？

编辑05.03.2019：

我使用https://stackoverflow.com/a/39907046/6330248的解决方案修复了它

Swift 4.2：

extension String {
    func components(withLength length: Int) -> [String] {
        guard length > 0 else {
            return [self]
        }

        return stride(from: 0, to: self.count, by: length).map {
            let start = self.index(self.startIndex, offsetBy: $0)
            let end = self.index(start, offsetBy: length, limitedBy: self.endIndex) ?? self.endIndex
            return String(self[start..<end])
        }
    }
}

func amIBeingDebugged() -> Bool {
    var info = kinfo_proc()
    var mib : [Int32] = [CTL_KERN, KERN_PROC, KERN_PROC_PID, getpid()]
    var size = MemoryLayout<kinfo_proc>.stride
    let junk = sysctl(&mib, UInt32(mib.count), &info, &size, nil, 0)
    assert(junk == 0, "sysctl failed")
    return (info.kp_proc.p_flag & P_TRACED) != 0
}

func FixedNSLog(_ format: String, _ args: CVarArg...) {

    let maxStringLength = 800
    let string = String(format: format, arguments: args)

    let substrings = string.components(withLength: maxStringLength)
    let substringsCount = substrings.count

    if substringsCount > 1 {
        NSLog("!!! WARNING !!! The following message is printed by \(substringsCount) parts, because of Xcode 10 console issues")
    }

    substrings.forEach { (substring) in
        NSLog(substring)
    }

}

func log(_ message: String) {
    if amIBeingDebugged() {
        FixedNSLog(message)
    }
    else {
        print(message)
    }
}