NSString用法

3、字符串比较

    NSString *str7 = @"hello000";
    NSString *str8 = [NSString stringWithString:str7];
    NSString *str9 = [NSString stringWithFormat:@"HE%@",@"llo00000"];

    NSLog(@"str7 >>>>> %p", str7);
    NSLog(@"str8 >>>>> %p", str8);
    NSLog(@"str9 >>>>> %p", str9);

    // str7和str9本质是两个指针，所以直接用==比较值
    if (str7 == str9) {
        NSLog(@"相等");
    } else {
        NSLog(@"不相等");
    }

    // 比较字符串内容是否一样
    if ([str7 isEqualToString:str9]) {
        NSLog(@"相等");
    } else {
        NSLog(@"不相等");
    }

    NSString *str12 = @"";

    NSString *str13 = @"";

    NSComparisonResult result1 = [str12 compare:str13 options:NSCaseInsensitiveSearch range:NSMakeRange(,)]; //options     选项  range 类别

    NSLog(@"result1 >>> %ld", result1);

4、字符串拼接

    NSString *str14 = @"hello";

    NSString *str15 = [str14 stringByAppendingString:@"lisi"];//append 附加，添加

    NSString *str16 = [@"/Users/nidediannaomingzi" stringByAppendingPathComponent:@"Desktop"];

5.字符串查找

    NSString *str17 = @"nice nice nice";
    if ([str17 containsString:@"nnnn"]) {
        NSLog(@"jin lai le");
    }//contains 包含，容纳

    NSString *str18 = @"410000xxxxxxxxxx";
    if ([str18 hasPrefix:@""]) {
        NSLog(@"shi de ");
    }// hasPrefix:方法的功能是判断创建的字符串内容是否以某个前缀开始

    NSString *str19 = @"icon.exe";
    if ([str19 hasSuffix:@"png"] || [str19 hasSuffix:@"jpg"]) {
        NSLog(@"合法头像");
    }//hasSuffix:方法的功能是判断创建的字符串内容是否以某个后缀开始  

    NSString *str20 = @"~/Desktop/test.h";

    NSLog(@"pathExtension >>> %@", [str20 pathExtension]);//  文件扩展名 Extension 扩展，扩大

    NSLog(@"absolute path >>> %@", [str20 stringByExpandingTildeInPath]); //Expand 展开   tilde波浪号

    NSLog(@"absolute path >>> %@", [[str20 stringByExpandingTildeInPath] stringByAbbreviatingWithTildeInPath]);  // 合闭波    浪号   abbreviate缩略 缩短

6、字符串截取

    NSString *str21 = @"hello, yangyang";

    NSLog(@"subString >>> %@", [str21 substringFromIndex:]);//sub 词根是‘子’    从第六个字符截取

    NSLog(@"subString >>> %@", [str21 substringToIndex:]);  // 截取六个字符

    NSLog(@"subString >>> %@", [str21 substringWithRange:NSMakeRange(, )]);  //字定义截取范围

    //截取？之后的
    NSRange sizeRange= [presaleGuideURL rangeOfString:@"?"];
    NSString *whatStr1 = [presaleGuideURL substringFromIndex:sizeRange.location+];
    NSLog(@"-->%@",whatStr1);//model=product&action=guidelines&goods_id=138206

    //截取到？
    NSString *whatStr2 = [presaleGuideURL substringToIndex:sizeRange.location];
    NSLog(@"-->%@",whatStr2);//http://rwandroid.shetest.cn/index.php

    //从？之后截取5位
    NSRange myRange = [presaleGuideURL rangeOfString:@"?"];
    myRange.length = ;
    NSString *whatStr3 = [presaleGuideURL substringWithRange:myRange];//?mode
    NSLog(@"-->%@",whatStr3);

7、字符串大小写转换

    NSString *enString = @"In our life, some love was doomed to no end, it is only responsible for the meeting.";
    NSLog(@"全大写------>%@", [enString uppercaseString]);
    NSLog(@"全小写------>%@", [enString lowercaseString]);
    NSLog(@"首字母大写--->%@", [enString capitalizedString]);

      全大写------>IN OUR LIFE, SOME LOVE WAS DOOMED TO NO END, IT IS ONLY RESPONSIBLE FOR THE MEETING.
      全小写------>in our life, some love was doomed to no end, it is only responsible for the meeting.
      首字母大写--->In Our Life, Some Love Was Doomed To No End, It Is Only Responsible For The Meeting.

    // 字母变换大小写时，中文字符被忽略，不会报错
    NSString *enChString = @"ps: 在我们一生中，有的爱情本来就注定没有结局，它只负责相遇。";
    NSLog(@"全大写------>%@", [enChString uppercaseString]);
    NSLog(@"全小写------>%@", [enChString lowercaseString]);
    NSLog(@"首字母大写--->%@", [enChString capitalizedString]);

    全大写------>PS: 在我们一生中，有的爱情本来就注定没有结局，它只负责相遇。
    全小写------>ps: 在我们一生中，有的爱情本来就注定没有结局，它只负责相遇。
    首字母大写--->Ps: 在我们一生中，有的爱情本来就注定没有结局，它只负责相遇。

/*********可变字符串*********/

    //NSMutableString *mstr = [NSMutableString stringWithCapacity:50];// Capacity容量

    //NSMutableString *mstr = [NSMutableString stringWithString:@"haha"];

    NSMutableString *mstr = [NSMutableString stringWithFormat:@"haha-%@-", @"xiaosan"];

1、追加

    [mstr appendString:@"zhang"];

    [mstr appendString:@"san"];

2.删除

   [mstr deleteCharactersInRange:NSMakeRange(, )];

3.插入

    [mstr insertString:@"haha" atIndex:];

4.替换

   [mstr replaceCharactersInRange:NSMakeRange(, ) withString:@"woshitihuan"];//从第五个字符开始用teacher替换4个字符 

5.格式化追加

    [mstr appendFormat:@"-%@", @"stage1"]; 

6、字符串赋值

    str31 = str30;

    [str31 appendString: @" 和字符串2"];