獲取沙盒中的Documents目錄路徑的三種代碼方式
// (1)
NSString *documentPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
// (2)
NSString *documentPath2 = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
// (3)
NSURL *documentURL = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
