URL与路径

主要解释以下两者区别
[NSURL URLWithString:filePath]
[NSURL fileURLWithPath:filePath];

一、概念
URL ：协议头 + 主机地址 + 资源路径 如果访问的地址是本机的，那么主机地址可以省略；路径是不用包含协议头和主机的

路径：？
二、测试

    NSDictionary *dic = @{@"name":@"xiaoqiang"};
    NSString *documentPath = [NSString stringWithFormat:@"%@/Documents",NSHomeDirectory()]; 
    NSString *filePath =  [NSString stringWithFormat:@"%@/name.plist",documentPath];
    
    NSString *fileURl =  [NSString stringWithFormat:@"file:///%@",filePath];
    //file:////Users/huihuadeng/Library/Developer/CoreSimulator/Devices/9F943056-7AD1-4A4E-B9E9-AE186A833AE6/data/Containers/Data/Application/188085CE-E77D-40CA-B419-566B2FCBD50A/Documents/name.plist
    NSURL *url1 = [NSURL URLWithString:fileURl];
//:file:///Users/huihuadeng/Library/Developer/CoreSimulator/Devices/9F943056-7AD1-4A4E-B9E9-AE186A833AE6/data/Containers/Data/Application/188085CE-E77D-40CA-B419-566B2FCBD50A/Documents/name.plist
    NSURL *url2 = [NSURL fileURLWithPath:filePath];
///Users/huihuadeng/Library/Developer/CoreSimulator/Devices/9F943056-7AD1-4A4E-B9E9-AE186A833AE6/data/Containers/Data/Appl ... me.plist
    NSURL *url3 = [NSURL URLWithString:filePath];
    
//    [dic writeToFile:filePath atomically:YES];//正常
    
//    [dic writeToURL:url1 error:nil];//正常
//   [dic writeToURL:url2 error:nil];//正常
  [dic writeToURL:url3 error:nil];//非正常

如上所述，推测 [NSURL URLWithString:filePath]; API仅仅是把string转化为URL对象，不做任何处理
[NSURL fileURLWithPath:filePath];会在路径前添加协议头 file:///

三、参考链接：https://www.jianshu.com/p/6997fd50f754