NSString *path = NSHomeDirectory();
上面的代碼得到的是應用程序目錄的路徑，在該目錄下有三個文件夾：Documents、Library、temp以及一個.app包！
該目錄下就是應用程序的沙盒，應用程序只能訪問該目錄下的文件夾！！！
請參考下面的例子：
1、
NSString *path1 = NSHomeDirectory();
NSLog(@"path1:%@", path1);
path1:/Users/yuanjun/Library/Application Support/iPhone Simulator/4.2/Applications/172DB70A-145B-4575-A31E-D501AC6EA830
2、
NSString *path2 = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
NSLog(@"path2:%@", path2);
path2:/Users/yuanjun/Library/Application Support/iPhone Simulator/4.2/Applications/172DB70A-145B-4575-A31E-D501AC6EA830/Library/Caches
3、
NSString *path3 = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSLog(@"path3:%@", path3);
path3:/Users/yuanjun/Library/Application Support/iPhone Simulator/4.2/Applications/172DB70A-145B-4575-A31E-D501AC6EA830/Documents
4、
NSString *path4 = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
NSLog(@"path4:%@", path4);
path4:/Users/yuanjun/Library/Application Support/iPhone Simulator/4.2/Applications/172DB70A-145B-4575-A31E-D501AC6EA830/Documents
5、
NSString *path5 = [NSHomeDirectory() stringByAppendingPathComponent:@"Library"];
NSLog(@"path5:%@", path5);
path5:/Users/yuanjun/Library/Application Support/iPhone Simulator/4.2/Applications/172DB70A-145B-4575-A31E-D501AC6EA830/Library
6、
NSString *path6 = [NSHomeDirectory() stringByAppendingPathComponent:@"temp"];
NSLog(@"path6:%@", path6);
path6:/Users/yuanjun/Library/Application Support/iPhone Simulator/4.2/Applications/172DB70A-145B-4575-A31E-D501AC6EA830/temp