无法使用Xcode 7.3.1在我的Swift 2项目中使用“ po”检查变量-错误加载帮助程序功能

当我在Xcode 7.3.1（使用标准Swift 2编译器）中运行我的Swift应用程序并且执行在断点处暂停时，我无法使用po命令检查变量。第一次运行po exists（exists在当前作用域中是非可选的Bool变量）时，我收到一条很长的错误消息（请参见下文）。从第二次开始运行相同命令开始，我收到error loading helper function: (null)消息。

该应用程序已在调试方案上编译并运行，没有“部署后处理”并且没有[-O0]优化。

变量内容正确显示在Xcode的变量检查器面板中。

po self在设备和iOS模拟器上运行的任何其他变量都出现相同的错误。

如果我运行一个新的干净项目，则调试po正常。

在当前范围内：

var exists: Bool = self.canRemoveAttachmentForEpisode(episode)
NSLog("Exists is now \(exists)") // Breakpoint is set here

这是在调试器面板中发生的事情：

po exists
error loading helper function: <EXPR>:141:9: warning: '--' is deprecated: it will be removed in Swift 3
        --maxItemCounter
        ^~
                         -= 1
<EXPR>:237:14: warning: '++' is deprecated: it will be removed in Swift 3
            i++
             ^~
              += 1
<EXPR>:267:19: warning: 'init(start:end:)' is deprecated: it will be removed in Swift 3.  Use the '..<' operator.
        let rng = Range(start: si, end: ei.advancedBy(-1))
                  ^
<EXPR>:280:9: warning: initialization of variable '$__lldb_error_result' was never used; consider replacing with assignment to '_' or removing it
    var $__lldb_error_result = __lldb_tmp_error
    ~~~~^~~~~~~~~~~~~~~~~~~~
    _
<EXPR>:89:41: error: 'CustomStringConvertible' is ambiguous for type lookup in this context
                    if let csc = (x as? CustomStringConvertible) {
                                        ^~~~~~~~~~~~~~~~~~~~~~~
Swift.CustomStringConvertible:13:17: note: found this candidate
public protocol CustomStringConvertible {
                ^
Castamatic.CustomStringConvertible:1:17: note: found this candidate
public protocol CustomStringConvertible {
                ^
<EXPR>:101:41: error: 'CustomStringConvertible' is ambiguous for type lookup in this context
                    if let csc = (x as? CustomStringConvertible) {
                                        ^~~~~~~~~~~~~~~~~~~~~~~
Swift.CustomStringConvertible:13:17: note: found this candidate
public protocol CustomStringConvertible {
                ^
Castamatic.CustomStringConvertible:1:17: note: found this candidate
public protocol CustomStringConvertible {
                ^


(lldb) 



(lldb) po exists
error loading helper function: (null)

(lldb)