路径解析

#import "FyQuestion.h"

@implementation FyQuestion

// 判断是绝对路径: 以 /开头的就是绝对路径
//   -->./ios/day1/
//  -->/oc/day
- (BOOL)isAbsolutePath:(NSString *)path {
    //直接利用判断开头的这样的方法 harPrefix
    return [path hasPrefix:@"/"];
}

// 取得路径path最后的部分 /home/xuanmac ---> xuanmac, /home/xuanmac/1.txt--->1.txt
- (NSString *)lastPathComponent:(NSString *)path {
    //第一步，判断是否末尾存在/
    int flag = 0;
    NSString * subStr = nil;
    if ([path hasSuffix:@"/"]) {
        //截取字符方法，subStringToIndex
        subStr = [path substringToIndex:[path length] - 1];
        flag = 1;
    }
    
    //利用查找字符串方法，option 是倒序查找
    //查找方法，返回的是一个范围
    NSRange range = {0,0};
    if (flag) {
        //NSBackwardsSearch 倒序查找的指令
        range = [subStr rangeOfString:@"/" options:NSBackwardsSearch];
        //substringFromIndex 从指定位置到字符串结尾，包括指定位置
        return [subStr substringFromIndex:range.location + 1];
    } else {
        range = [path rangeOfString:@"/" options:NSBackwardsSearch];
        return [path substringFromIndex:range.location + 1];
    }
}

// 删除路径path最后的部分 /home/xuanmac/ ---> /home, /home/xuanmac/1.txt--->/home/xuanmac
- (NSString *)stringByDeletingLastPathComponent:(NSString *)path {
    
    NSString * subStr =  nil;
    //判断path末尾是不是以/结尾
    if ([path hasSuffix:@"/"]) {
        subStr = [path substringToIndex:path.length - 1];
    } else {
        subStr = path;
    }
    
    //倒序查找
    NSRange range = [subStr rangeOfString:@"/" options:NSBackwardsSearch];
    
    NSString * str = [subStr substringToIndex:range.location];
    
    return [NSString stringWithString:str];
    
}
// 在路径上追加路径/home/xuanmac/ 和 demo/abc-->/home/xuanmac/demo/abc
- (NSString *)stringByAppendingPathComponent:(NSString *)path withPath:(NSString *)subPath {
    NSMutableString * mStr = [NSMutableString stringWithString:path];
    //判断是否是以/结尾
    if ([mStr hasSuffix:@"/"]) {
        if ([subPath hasPrefix:@"/"]) {
            [mStr appendString:[subPath substringFromIndex:1]];
        } else {
            [mStr appendString:subPath];
        }
        
    } else {
        if ([subPath hasPrefix:@"/"]) {
            [mStr appendFormat:@"/%@",[subPath substringFromIndex:1]];
        } else {
            [mStr appendFormat:@"/%@",subPath];
        }
    }
    
    return [NSString stringWithString:mStr];
}

// 取得文件的扩展名/home/xuanmac/1.txt --> txt
- (NSString *)pathExtension:(NSString *)path {
#if 1
    //pathExtension 获取路径拓展名
    NSString * str = path.pathExtension;
    return [NSString stringWithString:str];
#else
    NSRange range = [path rangeOfString:@"." options:NSBackwardsSearch];
    NSString * str = [path substringFromIndex:range.location + 1];
    return [NSString stringWithString:str];
#endif
}

// 删除文件扩展名/home/xuanmac/1.txt --> /home/xuanmac/1
- (NSString *)stringByDeletingPathExtension:(NSString *)path {
    NSRange range = [path rangeOfString:@"." options:NSBackwardsSearch];
    
    NSString * str = [path substringToIndex:range.location];
    return [NSString stringWithString:str];
}
// 去除里面多余的 /路径  Duplicate重复 Slash表示斜线
// path = @"///home//xuanmac/ios/oc/day1/"; 返回@"/home/xuanmac/ios/oc/day1"
- (NSString *) removeDuplicateSlash:(NSString *)path {
#if 1
    //看到//我们就要处理掉一个，知道在path没有// NSNotFound
    //path 转换成可变字符串
    NSMutableString * mStr = [NSMutableString stringWithString:path];
    
    while (1) {
        NSRange range = [mStr rangeOfString:@"//"];
        //判断是否还存在，如果不存在@"//",跳出循环
        if (NSNotFound == range.location) {
            break;
        }
        //每次都删除//当中的一个
        [mStr deleteCharactersInRange:NSMakeRange(range.location, 1)];
    }
    
    //处理完//之后，我们要处理路径末尾的/
    if([mStr hasSuffix:@"/"])
    {
        [mStr deleteCharactersInRange:NSMakeRange(mStr.length - 1, 1)];
    }
    
    return [NSString stringWithString:mStr];
#else 
    NSArray * array = [path componentsSeparatedByString:@"/"];
    NSMutableArray * mArray = [NSMutableArray arrayWithArray:array];
    [mArray removeObject:@""];
    
    return [mArray componentsJoinedByString:@"/"];//?????
#endif
}
//-获取路径中的所有目录名---->/home/xuanmac/ios/oc --->home  xuanmac  ios   oc
- (NSArray *)pathComponents:(NSString*)path {
    return [path componentsSeparatedByString:@"/"];
}

+ (void)test {
    FyQuestion * test = [[FyQuestion alloc] init];
    NSLog(@"第一题");
    NSLog(@"%hhd",[test isAbsolutePath:@"./ios/day1/"]);
    NSLog(@"%hhd",[test isAbsolutePath:@"/ios/day1/"]);
    
    NSLog(@"第二题");
    NSString * str1 = [test lastPathComponent:@"/ios/day1/"];
    NSLog(@"%@",str1);
    NSString * str2 = [test lastPathComponent:@"/ios/day1/1.txt"];
    NSLog(@"%@",str2);
    
    NSLog(@"第三题");
    NSString * str3 = [test stringByDeletingLastPathComponent:@"/ios/day1/"];
    NSLog(@"%@",str3);
    NSString * str4 = [test stringByDeletingLastPathComponent:@"/ios/day1/1.txt"];
    NSLog(@"%@",str4);
    
    NSLog(@"第四题");
    NSString * str5 = [test stringByAppendingPathComponent:@"/ios/day1/" withPath:@"1.txt"];
    NSLog(@"%@",str5);
    NSString * str6 = [test stringByAppendingPathComponent:@"/ios/day1" withPath:@"/test/1.txt"];
    NSLog(@"%@",str6);
    
    NSLog(@"第五题");
    NSLog(@"%@",[test pathExtension:@"/test/1.txt"]);
    
    NSLog(@"第六题");
    NSLog(@"%@",[test stringByDeletingPathExtension:@"/test/1.txt"]);
    NSLog(@"第七题");
    NSLog(@"%@",[test removeDuplicateSlash:@"/////////fdjkasj//fdhk///fdjsalfkjs///"]);
    NSLog(@"第八题");
    
    NSLog(@"第备用题");
}


@end