NSURL用於網路請求或本地檔案相關操作。

網路請求

初始化方法也不同：2個例項方法，2個類方法。

- (nullable instancetype)initWithString:(NSString *)URLString;
- (nullable instancetype)initWithString:(NSString *)URLString relativeToURL:(nullable NSURL *)baseURL NS_DESIGNATED_INITIALIZER;
+ (nullable instancetype)URLWithString:(NSString *)URLString;
+ (nullable instancetype)URLWithString:(NSString *)URLString relativeToURL:(nullable NSURL *)baseURL;
 

@property (nullable, readonly, copy) NSString *host;
@property (nullable, readonly, copy) NSNumber *port;
@property (nullable, readonly, copy) NSString *user;
@property (nullable, readonly, copy) NSString *password;
@property (nullable, readonly, copy) NSString *path;
@property (nullable, readonly, copy) NSString *fragment;
@property (nullable, readonly, copy) NSString *parameterString;
@property (nullable, readonly, copy) NSString *query;
@property (nullable, readonly, copy) NSString *relativePath; // The same as path if baseURL is nil
 

檔案初始化方法：

- (instancetype)initFileURLWithPath:(NSString *)path isDirectory:(BOOL)isDir relativeToURL:(nullable NSURL *)baseURL NS_AVAILABLE(10_11, 9_0) NS_DESIGNATED_INITIALIZER;
/* Initializes a newly created file NSURL referencing the local file or directory at path, relative to a base URL.
 */
- (instancetype)initFileURLWithPath:(NSString *)path relativeToURL:(nullable NSURL *)baseURL NS_AVAILABLE(10_11, 9_0) NS_DESIGNATED_INITIALIZER; // Better to use initFileURLWithPath:isDirectory:relativeToURL: if you know if the path is a directory vs non-directory, as it saves an I/O.

- (instancetype)initFileURLWithPath:(NSString *)path isDirectory:(BOOL)isDir NS_AVAILABLE(10_5, 2_0) NS_DESIGNATED_INITIALIZER;
- (instancetype)initFileURLWithPath:(NSString *)path NS_DESIGNATED_INITIALIZER;  // Better to use initFileURLWithPath:isDirectory: if you know if the path is a directory vs non-directory, as it saves an i/o.

/* Initializes and returns a newly created file NSURL referencing the local file or directory at path, relative to a base URL.
 */
+ (NSURL *)fileURLWithPath:(NSString *)path isDirectory:(BOOL) isDir relativeToURL:(nullable NSURL *)baseURL NS_AVAILABLE(10_11, 9_0);
/* Initializes and returns a newly created file NSURL referencing the local file or directory at path, relative to a base URL.
 */
+ (NSURL *)fileURLWithPath:(NSString *)path relativeToURL:(nullable NSURL *)baseURL NS_AVAILABLE(10_11, 9_0); // Better to use fileURLWithPath:isDirectory:relativeToURL: if you know if the path is a directory vs non-directory, as it saves an I/O.

+ (NSURL *)fileURLWithPath:(NSString *)path isDirectory:(BOOL)isDir NS_AVAILABLE(10_5, 2_0);
+ (NSURL *)fileURLWithPath:(NSString *)path; // Better to use fileURLWithPath:isDirectory: if you know if the path is a directory vs non-directory, as it saves an i/o.

/* Initializes a newly created URL referencing the local file or directory at the file system representation of the path. File system representation is a null-terminated C string with canonical UTF-8 encoding.
 */
- (instancetype)initFileURLWithFileSystemRepresentation:(const char *)path isDirectory:(BOOL)isDir relativeToURL:(nullable NSURL *)baseURL NS_AVAILABLE(10_9, 7_0) NS_DESIGNATED_INITIALIZER;