将NSString转换为char *时找不到文件

Question

So I have a platform independent API that loads a file, it takes a char* as a value. I wrote some test code in the GetResource function that used a string literal and it worked fine. However when I convert over to using the char* and converting back to an NSString the file can't be found.

Working code:

bool GetResource(const char* filePath, uint8*& allocatedBuffer, uint32& size) {

    bool success = false;
    NSString* path = [[NSBundle mainBundle] pathForResource: "models/testModel" ofType: @"obj"];

Not Working code:

NSString* nsModelString = @"models/testModel";
gDatastore->GetResource([nsModelString UTF8String], buffer, size);

....

bool GetResource(const char* filePath, uint8*& allocatedBuffer, uint32& size) {

    bool success = false;
    NSString* nsFilePath = [NSString stringWithFormat:@"%c" , filePath];
    NSString* path = [[NSBundle mainBundle] pathForResource: nsFilePath ofType: @"obj"];

Can anyone tell me what I am using wrong? Is there an easy way to look at an NSString and see the contents?

Answer 1

To look at the NSString to see the contents, you could either view it in the debugger or use:

NSLog(@"nsFilePath: %@", nsFilePath);

I think at least part of the problem is on this line:

NSString* nsFilePath = [NSString stringWithFormat:@"%c" , filePath];

%c is the format specifier for a single 8-bit unsigned char. For a C style string, you probably want to use %s , which is the format specifier for a null-terminated array of 8-bit unsigned characters.

Also, a more straightforward way of converting from a C string to an NSString is by using the + (id)stringWithCString:(const char *)cString encoding:(NSStringEncoding)enc method of the NSString class. See the NSString class reference for more details.