stringByAppendingPathComponent及他的删除函数 等系列函数

- (NSString *)stringByAppendingPathComponent:(NSString *)aString

aString is “scratch.tiff”:

Receiver’s String Value	Resulting String
“/tmp”	“/tmp/scratch.tiff”
“/tmp/”	“/tmp/scratch.tiff”
“/”	“/scratch.tiff”
“” (an empty string)	“scratch.tiff”

- (NSString *)stringByDeletingLastPathComponent

Receiver’s String Value	Resulting String
“/tmp/scratch.tiff”	“/tmp”
“/tmp/lock/”	“/tmp”
“/tmp/”	“/”
“/tmp”	“/”
“/”	“/”
“scratch.tiff”	“” (an empty string)

- (NSString *)stringByAppendingPathExtension:(NSString *)ext

ext is "tiff"

Receiver’s String Value	Resulting String
“/tmp/scratch.old”	“/tmp/scratch.old.tiff”
“/tmp/scratch.”	“/tmp/scratch..tiff”
“/tmp/”	“/tmp.tiff”
“scratch”	“scratch.tiff”

- (NSString *)stringByDeletingPathExtension




Receiver’s String Value	Resulting String
“/tmp/scratch.tiff”	“/tmp/scratch”
“/tmp/”	“/tmp”
“scratch.bundle/”	“scratch”
“scratch..tiff”	“scratch.”
“.tiff”	“.tiff”
“/”	“/”

- (NSString *)stringByAppendingString:(NSString *)aString

aString

The string to append to the receiver. This value must not be nil.

NSString *errorTag = @"Error: ";

NSString *errorString = @"premature end of file.";

NSString *errorMessage = [errorTag stringByAppendingString:errorString];

produces the string “Error: premature end of file.”.