Objective--C之NSString常用方法

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{
    @autoreleasepool
    {
#pragma mark - NSString
        char *s = "Hello Objective-C";//C语言的字符串格式
        NSString *str = @"Hello";
        //OC、C字符串的转换：C-->OC
        NSString *str1 = [NSString stringWithUTF8String:s];//UTF8是一种编码格式
        NSLog(@"str1 = %@", str1);
        //OC-->C
        NSLog(@"str2 = %s", [str UTF8String]);
        
        //创建字符串
        NSString *str3 = @"IOS";
        NSString *str4 = [[NSString alloc] init];
        str4 = @"IOS";
        // 格式化字符串
        int a = 10;
        int b = 20;
        NSString *str5 = [NSString stringWithFormat:@"a = %d b = %d", a, b];
        NSLog(@"str5 = %@", str5);
        //拼接字符串
        NSString *str6 = [[str5 stringByAppendingString:@" and "] stringByAppendingString:str3];
        NSLog(@"str6 = %@", str6);
        //大小写转换
        //转换小写
        NSString *str7 = @"aBcdEFG";
        NSString *str8 = [str7 lowercaseString];
        NSLog(@"str8 = %@", str8);
        //转换大写
        NSString *str9 = [str7 uppercaseString];
        NSLog(@"str9 = %@", str9);
        
        //前缀和后缀的判断
        NSString *str10 = @"www.songlei.com";
        //判断前缀
        BOOL hasPrefix = [str10 hasPrefix:@"www."];
        if (hasPrefix)
        {
            NSLog(@"有对应前缀");
        }
        else
        {
            NSLog(@"没有对应前缀");
        }
        //判断后缀
        BOOL hasSuffix = [str10 hasSuffix:@".com"];
        if (hasSuffix)
        {
            NSLog(@"有对应后缀");
        }
        else
        {
            NSLog(@"没有对应后缀");
        }
        
        //判断两个字符串是否相同
        NSString *str11 = @"Hello";
        NSString *str12 = @"Hello ";
        if ([str11 isEqualToString:str12])
        {
            NSLog(@"两个字符串一致");
        }
        else
        {
            NSLog(@"两个字符串不一致");
        }
        
        //***比较字符串***
//        NSComparisonResult
        
        //分割//按照指定字符分割字符串
        NSString *str13 = @"a, b, c, d, e, f";
        NSArray *strArray = [str13 componentsSeparatedByString:@", "];
        for (NSString *str in strArray)
        {
            NSLog(@"str = %@", str);
        }
        //按照指定范围分割字符串
        NSRange range = NSMakeRange(3, 9);
        NSString *str14 = [str13 substringWithRange:range];
        NSLog(@"str14 = %@", str14);
        //从某一位开始截取后面的字符串
        NSString *str15 = [str13 substringFromIndex:9];
        NSLog(@"str15 = %@", str15);
        //从开头截取到某一位
        NSString *str16 = [str13 substringToIndex:9];
        NSLog(@"str16 = %@", str16);
        //将字符串拆分为每一个字符
        int j = (int)[str13 length];
        for(int i = 0; i < j; ++i)
        {
            NSLog(@"%c", [str13 characterAtIndex:i]);
        }
        
        //查找
        NSString *str17 = @"ab cd ef gh ij ab";
        //查找指定字符串的位置
        NSRange range1 = [str17 rangeOfString:@"ab"];//(这个查找是一个正向查找)
        NSLog(@"range1.location:%ld range1.length:%ld", range1.location, range1.length);
        
        //替换
        NSString *str18 = @"Hello huashan, Hello songlei";
        //替换某一个范围的内容
        NSString *str19 = [str18 stringByReplacingCharactersInRange:NSMakeRange(0, 5) withString:@"你好"];
        NSLog(@"str19 = %@", str19);
        //用指定字符串替换字符串中的子串
        /*
         stringByReplacingOccurrencesOfString - 源字符串中要被替换的内容 withString - 替换字符串
         */
        NSString *str20 = [str18 stringByReplacingOccurrencesOfString:@"Hello" withString:@"Hi"];
        NSLog(@"str20 = %@", str20);
        
#pragma mark - NSURL(路径类)
        // 读取文件
        //文件来源：1.本地文件。2.网络文件
        //路径类
        NSString *str21 = @"www.baidu.com";
        //网络路径
        NSURL *httpURL = [NSURL URLWithString:str21];
        //本地路径
        NSURL *fileURL = [NSURL fileURLWithPath:str21];
        //读取网络文件
        NSString *httpStr = [NSString stringWithContentsOfURL:httpURL encoding:NSUTF8StringEncoding error:nil];
        NSLog(@"httpURL = %@", httpStr);
        //读取本地文件
        NSString *fileStr = [NSString stringWithContentsOfFile:@"/Users/hskj/Desktop/Test.txt" encoding:NSUTF8StringEncoding error:nil];    //Test.txt自己创建的纯文本文件，放在了桌面上
        NSLog(@"fileStr = %@", fileStr);    //fileStr = Hello IOS Songlei
        
        //写入文件
        NSString *str22 = @"Hello TravelColor";
        BOOL isOk = [str22 writeToFile:@"/Users/hskj/Desktop/Demo.txt" atomically:YES encoding:NSUTF8StringEncoding error:nil];
        if (isOk)
        {
            NSLog(@"文件写入成功");
        }
        else
        {
            NSLog(@"文件写入失败");
        }
        
    }
    return 0;
}

2016-08-10 14:42:32.165 FoundationFrame[1117:177889] str1 = Hello Objective-C
2016-08-10 14:42:32.166 FoundationFrame[1117:177889] str2 = Hello
2016-08-10 14:42:32.166 FoundationFrame[1117:177889] str5 = a = 10 b = 20
2016-08-10 14:42:32.166 FoundationFrame[1117:177889] str6 = a = 10 b = 20 and IOS
2016-08-10 14:42:32.167 FoundationFrame[1117:177889] str8 = abcdefg
2016-08-10 14:42:32.167 FoundationFrame[1117:177889] str9 = ABCDEFG
2016-08-10 14:42:32.167 FoundationFrame[1117:177889] 有对应前缀
2016-08-10 14:42:32.167 FoundationFrame[1117:177889] 有对应后缀
2016-08-10 14:42:32.167 FoundationFrame[1117:177889] 两个字符串不一致
2016-08-10 14:42:32.167 FoundationFrame[1117:177889] str = a
2016-08-10 14:42:32.167 FoundationFrame[1117:177889] str = b
2016-08-10 14:42:32.167 FoundationFrame[1117:177889] str = c
2016-08-10 14:42:32.167 FoundationFrame[1117:177889] str = d
2016-08-10 14:42:32.167 FoundationFrame[1117:177889] str = e
2016-08-10 14:42:32.167 FoundationFrame[1117:177889] str = f
2016-08-10 14:42:32.168 FoundationFrame[1117:177889] str14 = b, c, d, 
2016-08-10 14:42:32.168 FoundationFrame[1117:177889] str15 = d, e, f
2016-08-10 14:42:32.168 FoundationFrame[1117:177889] str16 = a, b, c, 
2016-08-10 14:42:32.168 FoundationFrame[1117:177889] a
2016-08-10 14:42:32.168 FoundationFrame[1117:177889] ,
2016-08-10 14:42:32.168 FoundationFrame[1117:177889]  
2016-08-10 14:42:32.168 FoundationFrame[1117:177889] b
2016-08-10 14:42:32.168 FoundationFrame[1117:177889] ,
2016-08-10 14:42:32.168 FoundationFrame[1117:177889]  
2016-08-10 14:42:32.169 FoundationFrame[1117:177889] c
2016-08-10 14:42:32.169 FoundationFrame[1117:177889] ,
2016-08-10 14:42:32.169 FoundationFrame[1117:177889]  
2016-08-10 14:42:32.169 FoundationFrame[1117:177889] d
2016-08-10 14:42:32.169 FoundationFrame[1117:177889] ,
2016-08-10 14:42:32.169 FoundationFrame[1117:177889]  
2016-08-10 14:42:32.169 FoundationFrame[1117:177889] e
2016-08-10 14:42:32.169 FoundationFrame[1117:177889] ,
2016-08-10 14:42:32.169 FoundationFrame[1117:177889]  
2016-08-10 14:42:32.169 FoundationFrame[1117:177889] f
2016-08-10 14:42:32.169 FoundationFrame[1117:177889] range1.location:0 range1.length:2
2016-08-10 14:42:32.169 FoundationFrame[1117:177889] str19 = 你好 huashan, Hello songlei
2016-08-10 14:42:32.170 FoundationFrame[1117:177889] str20 = Hi huashan, Hi songlei
2016-08-10 14:42:32.186 FoundationFrame[1117:177889] httpURL = (null)
2016-08-10 14:42:32.186 FoundationFrame[1117:177889] fileStr = Hello IOS Songlei
2016-08-10 14:42:32.245 FoundationFrame[1117:177889] 文件写入成功
Program ended with exit code: 0