iphone - 调用-createDirectoryAtURL : causes crash

Question

我现在很迷茫。这是我的一段代码:

NSFileManager *manager = [NSFileManager defaultManager];

NSURL *backup = [self applicationDocumentsDirectory];
backup = [backup URLByAppendingPathComponent:@"Old_Data_File"];

[manager createDirectoryAtURL:backup withIntermediateDirectories:YES attributes:nil error:nil];

执行此代码时，它会在消息的最后一行崩溃

-[NSFileManager createDirectoryAtURL:withIntermediateDirectories:attributes:error:]: unrecognized selector sent to instance 0x5e59220

这怎么可能是无法识别的选择器？

编辑:

manager 不是 nil 并且打印 backup 到控制台导致

{type = 15, string = file://localhost/Users/fabian/Library/Application%20Support/iPhone%20Simulator/4.3.2/Applications/D37C5B93-A778-4555-8953-814F823B1116/Documents/Old_Data_File, encoding = 134217984, base = (null)}

直到 Old_Data_File 路径存在，最后一个组件应该由文件管理器创建...

Answer 1

哦...您的目标是 iOS 5.0 及更高版本吗？此 API 在 iOS 4.3 上不存在。