从库中调用类别方法时"无法识别的选择器发送到类"

Question

问题

这个问题可能看起来有点长,但我尽量提供尽可能多的信息,因为我对此非常感兴趣.

我目前正在开发一个应该自动执行XML文档解析的库.但是我现在遇到了第一次测试库的问题.

我有一个名为library的库类CSXDocumentLayout,它表示文档的布局.此类包含- (NSError *)readLayoutDocument:(NSString *)fpath从init方法调用的私有方法.

/* MARK: Reading in Layouts */
- (NSError *)readLayoutDocument:(NSString *)fpath {
    CSXDocumentLayout *layout;
    CSXXMLParser *parser;
    BOOL state;

    layout = [CSXDocumentLayout layoutDocumentLayout];

    parser = [[CSXXMLParser alloc] initWithDocumentLayouts:
              [NSArray arrayWithObject:layout]];
    parser.file = fpath;

    state = [parser parse];

    if(state == NO || parser.error != nil) {
        return parser.error;
    }
    return nil;
}

此方法将读入表示其他XML文档布局的XML文档.它由类解析CSXXMLParser,我想测试它.

我创建了一个表示布局文档的对象+[CSXDocumentLayout layoutDocumentLayout].此方法在类别中实现CSXDocumentLayout (CSXLayoutObject).

以下是我的测试文件:

#import <Foundation/Foundation.h>
#import <CeasyXML.h>

int main(int argc, const char **argv) {
    NSAutoreleasePool *pool = [NSAutoreleasePool new];

    NSString *file;

    file = [NSString stringWithUTF8String:__FILE__];
    file = [file stringByDeletingLastPathComponent];
    file = [file stringByAppendingPathComponent:@"Layout.xml"];

    CSXDocumentLayout *layout;
    NSError *error;

    layout = [[CSXDocumentLayout alloc] initWithLayoutDocument:file 
                                                         error:&error];
    if(layout == nil) {
        NSLog(@"Could not create layout: %@", error);
        exit(0);
    }

    NSLog(@"Layout:\n%@", layout);

    [pool release];
    return 0;
}

此文件编译为链接到我的静态库libceasyxml.a的单独可执行文件.一切都很好,没有任何警告.

但是当我运行它时,我得到一个无法识别的选择器发送到类异常:

2012-05-02 16:59:47.620 TestApp[1887:a0f] +[CSXDocumentLayout layoutDocumentLayout]: unrecognized selector sent to class 0x1000064c8
2012-05-02 16:59:47.791 TestApp[1887:a0f] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[CSXDocumentLayout layoutDocumentLayout]: unrecognized selector sent to class 0x1000064c8'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x00007fff83e47784 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x00007fff84604f03 objc_exception_throw + 45
    2   CoreFoundation                      0x00007fff83ea11a0 __CFFullMethodName + 0
    3   CoreFoundation                      0x00007fff83e198ef ___forwarding___ + 751
    4   CoreFoundation                      0x00007fff83e15a38 _CF_forwarding_prep_0 + 232
    5   TestApp                             0x0000000100001512 -[CSXDocumentLayout(Private) readLayoutDocument:] + 49
    6   TestApp                             0x00000001000010d4 -[CSXDocumentLayout initWithLayoutDocument:error:] + 96
    7   TestApp                             0x0000000100001017 main + 179
    8   TestApp                             0x0000000100000f5c start + 52
    9   ???                                 0x0000000000000001 0x0 + 1
)

我觉得很不安,我不能调用类的方法+[CSXDocumentLayout(CSXLayoutObject) layoutDocumentLayout],但我可以打电话都-[CSXDocumentLayout initWithLayoutDocument:error:]和-[CSXDocumentLayout(Private) readLayoutDocument:].

研究

我检查了是否通过运行在输出文件中定义了方法nm file,并且部分原因是:

在libceasyxml.a中,它被定义(nm libceasyxml.a)

...
libceasyxml.a(CSXDocumentLayout+CSXLayoutObject.o):
0000000000000100 t +[CSXDocumentLayout(CSXLayoutObject) classAttributeLayout]
00000000000020e0 s +[CSXDocumentLayout(CSXLayoutObject) classAttributeLayout].eh
000000000000056b t +[CSXDocumentLayout(CSXLayoutObject) documentElementLayout]
0000000000002180 s +[CSXDocumentLayout(CSXLayoutObject) documentElementLayout].eh
0000000000000402 t +[CSXDocumentLayout(CSXLayoutObject) layoutDocumentLayout]
0000000000002148 s +[CSXDocumentLayout(CSXLayoutObject) layoutDocumentLayout].eh
0000000000000200 t +[CSXDocumentLayout(CSXLayoutObject) layoutElementLayout]
0000000000002110 s +[CSXDocumentLayout(CSXLayoutObject) layoutElementLayout].eh
0000000000000000 t +[CSXDocumentLayout(CSXLayoutObject) nameAttributeLayout]
00000000000020b0 s +[CSXDocumentLayout(CSXLayoutObject) nameAttributeLayout].eh
0000000000002098 s EH_frame1
0000000000001c49 s LC0
...

在TestApp中,它未定义(nm TestApp),实际上我找不到任何带有类别名称的方法CSXLayoutObject.

...
0000000100001271 t -[CSXDocumentLayout setDocumentClassString:]
00000001000013a8 t -[CSXDocumentLayout setElements:]
0000000100001490 t -[CSXDocumentLayout setName:]
00000001000014db t -[CSXDocumentLayout(Private) readLayoutDocument:]
0000000100004060 t -[CSXElementList dealloc]
00000001000040b0 t -[CSXElementList elements]
...

Answer 1

我怀疑你遇到了静态库中嵌入的已知类别问题.

如果我是对的,尝试使用链接器标志进行编译-ObjC(如果这还不够,那么-all_load)问题就会消失.