我们常常需要优化控制台的输出样式，比如方法名，方法行数等，这时候可以使用一些常用的dlog，在swift 3.0中，可以这样定义：

//MARK: Macros

/** 
dLog macros to abbreviate NSLog.
    
Use like this:

dLog("Log this!")
**/

#if DEBUG
    func dLog<T>(_ object: T, filename: String = #file, function: String = #function, line: Int = #line) {
        let fileString = filename as NSString
        let fileLastPathComponent = fileString.lastPathComponent as NSString
        let filename = fileLastPathComponent.deletingPathExtension
        
        print("[\(filename):\(line)] \(function) - \(object)")
    }
#else
    func dLog<T>(_ object: T, filename: String = #file, function: String = #function, line: Int = #line) {
        
    }
#endif

输出样式如下：

time xx[xx:xx] [filename: line] function() - a called
time xx[xx:xx] [filename: line] function() - b called

参考资料：[https://github.com/ArtSabintsev/Magic/blob/master/Magic.swift]