objective-c - 感叹号对快速初始化程序意味着什么？

我已经看到了Xcode从Objective-C初始化程序创建的代码:

init!(logMsg: String!, level logLevel: DDLogLevel, flag logFlag: DDLogFlag, context logContext: Int32, file: UnsafePointer<Int8>, function: UnsafePointer<Int8>, line: Int32, tag: AnyObject!, options optionsMask: DDLogMessageOptions)
init!(logMsg: String!, level logLevel: DDLogLevel, flag logFlag: DDLogFlag, context logContext: Int32, file: UnsafePointer<Int8>, function: UnsafePointer<Int8>, line: Int32, tag: AnyObject!, options optionsMask: DDLogMessageOptions, timestamp aTimestamp: NSDate!)

原始代码是:

- (instancetype)initWithLogMsg:(NSString *)logMsg
                         level:(DDLogLevel)logLevel
                          flag:(DDLogFlag)logFlag
                       context:(int)logContext
                          file:(const char *)file
                      function:(const char *)function
                          line:(int)line
                           tag:(id)tag
                       options:(DDLogMessageOptions)optionsMask;
- (instancetype)initWithLogMsg:(NSString *)logMsg
                         level:(DDLogLevel)logLevel
                          flag:(DDLogFlag)logFlag
                       context:(int)logContext
                          file:(const char *)file
                      function:(const char *)function
                          line:(int)line
                           tag:(id)tag
                       options:(DDLogMessageOptions)optionsMask
                     timestamp:(NSDate *)aTimestamp;

在 init 关键字之后，感叹号是什么意思？

最佳答案

它是失败的初始化程序，在Swift 1.1(与Xcode 6.1一起引入)中

从Apple Developer:



(强调我的)

关于objective-c - 感叹号对快速初始化程序意味着什么？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/26440520/