Tuesday, May 14, 2013

NSString getFileSystemRepresentation maxLength example ios

[NSString getFileSystemRepresentation maxLength]

Interprets the receiver as a system-independent path and fills a buffer with a C-string in a format and encoding suitable for use with file-system calls.
- (BOOL)getFileSystemRepresentation:(char *)buffer maxLength:(NSUInteger)maxLength
Parameters of [NSString getFileSystemRepresentation maxLength]
Upon return, contains a C-string that represent the receiver as as a system-independent path, plus the NULLtermination byte. The size of buffer must be large enough to contain maxLength bytes.
The maximum number of bytes in the string to return in buffer (including a terminating NULL character, which this method adds).
Return Value of [NSString getFileSystemRepresentation maxLength]
YES if buffer is successfully filled with a file-system representation, otherwise NO (for example, if maxLength would be exceeded or if the receiver can’t be represented in the file system’s encoding).
Discussion of [NSString getFileSystemRepresentation maxLength]
This method operates by replacing the abstract path and extension separator characters (‘/’ and ‘.’ respectively) with their equivalents for the operating system. If the system-specific path or extension separator appears in the abstract representation, the characters it is converted to depend on the system (unless they’re identical to the abstract separators).
Note that this method only works with file paths (not, for example, string representations of URLs).
Example of [NSString getFileSystemRepresentation maxLength]
The following example illustrates the use of the maxLength argument. The first method invocation returns failure as the file representation of the string (@"/mach_kernel") is 12 bytes long and the value passed as the maxLengthargument (12) does not allow for the addition of a NULL termination byte.[NSString getFileSystemRepresentation maxLength]
char filenameBuffer[13];
BOOL success;
success = [@"/mach_kernel" getFileSystemRepresentation: filenameBuffer maxLength:12];
// success == NO
// Changing the length to include the NULL character does work
success = [@"/mach_kernel" getFileSystemRepresentation: filenameBuffer maxLength:13];
// success == YES