objective-c - appendBezierPathWithGlyph 在 [NSBezierPath currentPoint] 中失败

Question

有人知道在什么情况下会发生这种情况吗？

GDB 输出:

0 .. 8:  kill, abort, objc_exception_throw etc.
9:  0x00007fff87ea21f4 in +[NSException raise:format:] ()
10: 0x00007fff8694e9e2 in -[NSBezierPath currentPoint] ()
11: 0x00007fff869e3b3b in __NSAppendBezierPathWithGlyphs ()
12: 0x00007fff869e5baf in -[NSBezierPath appendBezierPathWithGlyphs:count:inFont:]()
13: 0x00007fff869e2e2d in -[NSBezierPath appendBezierPathWithGlyph:inFont:] ()

Answer 1

objc_exception_throw 是抛出异常的函数。在这种情况下，有两件事需要查看:控制台日志(它将识别异常本身)和导致 objc_exception_throw 的调用堆栈。

在这种情况下，我可以仅从调用堆栈猜测异常是什么:如果路径没有当前点，则 currentPoint 将抛出。这是由 the documentation for the appendBezierPathWithGlyphs:count:inFont: method 支持的(以及 for the method you're directly calling ):

You must set the path's current point (using the moveToPoint: method or through the creation of a preceding line or curve segment) before you invoke this method.