OC学习----可变字符串

OC学习4

可变字符串学习

    /*     开学 OC 中 Foundation 框架下的基础类     */    /* NSValue和NSNumber        功能     将 OC 和 C 语言当中的基本数据类型转换成实例对象,即将值类型转换成引用类型     NSValue 为NSNumber的父类     其中NSValue类可以将CGPoint,CGSize,CGRect,NSRange,NSEdgeInsets转换成对象     其中NSNumber类可以将int,float,double,char,bool等 C 中的基本数据类型转换对象     我们将 C 和 OC 中的基本数据类型(值类型)转换成对象(引用类型)的过程,叫做封装.相对应的,也有一个将对象转变成基本数据类型,此过程叫做拆包.     字符串操作:     1.字符串长度     2.字符串的截取     3.字符串比较        "=="表示两个字符串的指针和内容都相同        "xxx isEqualToString:yyy"表示两个字符串内容是否相同     4.根据字符串拿到对应的range     5.判断字符串中是否有XX前缀或XX后缀     6.字符串拼接     note:字符串操作的代码实现在下面.     */    //以下为基本数据类型

        int a = 5;        float b = 4.5;        double c = 3.14;        char d = 'c';        bool flag = YES;  //      CGPoint point = {3,4};//      CGSize size = {30,47};//宽和高//      CGRect rect = {point,size}; 

    //以上注释的3种,通常不以这种方式来编写

        CGPoint point = CGPointMake(3, 4);        CGSize size = CGSizeMake(30, 47);        CGRect rect = CGRectMake(1, 2, 3, 4);        NSRange range = NSMakeRange(3, 7);   

    //转换

        NSValue *pointValue = [NSValue valueWithPoint:point];        NSValue *sizeValue = [NSValue valueWithSize:size];        NSValue *rectValue = [NSValue valueWithRect:rect];        NSValue *rangeValue = [NSValue valueWithRange:range];        NSNumber *intNumber = [NSNumber numberWithInt:1];        NSNumber *integerNumber = [NSNumber numberWithInteger:12];        NSNumber *floatNumber = [NSNumber numberWithFloat:12.3];        NSNumber *doubleNumber = [NSNumber numberWithDouble:12.45];        NSNumber *charNumber = [NSNumber numberWithChar:'b'];        NSNumber *boolNumber = [NSNumber numberWithBool:YES]; 

    //拆包

        CGPoint point1 = [pointValue pointValue];        CGSize size1 = [sizeValue sizeValue];        CGRect rect1 = [rectValue rectValue];        NSRange range1 = [rangeValue rangeValue];        int a1 = [intNumber intValue];        NSInteger a2 = [integerNumber integerValue];        float a3 = [floatNumber floatValue];        double a4 = [doubleNumber doubleValue];        char a5 = [charNumber charValue];        bool a6 = [boolNumber boolValue];  

    //NSString 和 NSMutableString    /*OC中的字符串具有强大的功能,即封装性极强,我们只需要找到对应API(API指的是功能,方法),就可以对字符串做相应的操作.OC中字符串分为不可亦字符串和可变字符串,其中可变字符串是不可变字符串的子类.     在ios开发中,字符串通常用作显示文本,即作为UILable,UITextFeild等一些UIKit框架下控件的显示文本     */    /*     NSString 不可变字符串        1.快速初始化

   NSString *string1 = @"bokanwisdom"; 

        2.格式化的方式初始化

               NSString *string4 = [NSString stringWithFormat:@"%d",3]; 

        note:对于用格式化方式来构造字符串实例来讲,其作用并不仅仅来构造一个字符串对象,它还可以用来做字符串拼接        3.从本地文件中读取字符串

            NSString *string8 = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:&error];            NSString *string9 = [NSString stringWithContentsOfFile:path usedEncoding:&encoding error:&error];  

        4.从网络中读取一个字符串

            NSURL *url = [NSURL URLWithString:@"http://www.baidu.com"];            NSString *string10 = [NSString stringWithContentsOfURL:url encoding:4 error:&error];    

    //1.初始化一个字符串对象

        NSString *string1 = @"bokanwisdom";        NSString *string2 = [NSString stringWithString:@"bokanwisdom"];        NSString *string3 = [[NSString alloc] initWithString:@"bokanwisdom"];        NSString *string4 = [NSString stringWithFormat:@"%d",3];//把整型数字3转换成字符串        NSString *string5 = [NSString stringWithFormat:@"%dbokanwisdom",3];        NSLog(@"string4 = %@",string5);  

    //对于用格式化方式来构造字符串实例来讲,其作用并不仅仅来构造一个字符串对象,它还可以用来做字符串拼接

        NSString *string6 = @"XXX";        NSString *string7 = @"bbb";        NSString *newString = [NSString stringWithFormat:@"%@%@",string6,string7];        NSLog(@"%@",newString);   

    //在本地文件中读取字符串,并且知道该文件的编码方式

        NSString *path = @"/Users/4001/Desktop/test.html";        NSError *error;        NSString *string8 = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:&error];        NSLog(@"%@",string8);

    //在本地文件中读取字符串,但不知道该文件的编码方式

        NSStringEncoding encoding;        NSString *string9 = [NSString stringWithContentsOfFile:path usedEncoding:&encoding error:&error];        NSLog(@"%@,%lu",string9,(unsigned long)encoding);  

    //从网络文件中读取字符串

        NSURL *url = [NSURL URLWithString:@"http://www.baidu.com"];        NSString *string10 = [NSString stringWithContentsOfURL:url encoding:4 error:&error];        NSLog(@"string10 = %@",string10);   

    //字符串的操作

          NSString *string11 = @"当女朋友说“随便”的时候，她的意思其实是：老娘懒得去想，也想不出好的，虽然是让你看着办，但你一定要想出我满意的才行";  

    //字符串截取

        NSString *subStr = [string11 substringToIndex:8];//从0开始到第8个        NSLog(@"subStr = %@",subStr);        NSString *subStr1 = [string11 substringFromIndex:8];//从第8个开始        NSLog(@"subStr1 = %@",subStr1);        NSString *subStr2 = [string11 substringWithRange:NSMakeRange(8, (string11.length) - 8)];//从第5个开始,截取10个字符        NSLog(@"subStr2 = %@",subStr2);

    //字符串的属性 长度 length    //字符串比较 如何判断两个字符串是否相等?

           if (subStr2 == subStr1) {            //内容和指针都相等时,才成立            NSLog(@"subStr1 和 subStr2 相等");        }else{            NSLog(@"subStr1 和 subStr2 不相等");        }

    //在实际开发过程中,我们通常只需要比较两个字符串的内容是否相等

            if ([subStr1 isEqualToString:subStr2]) {            NSLog(@"subStr1 和 subStr2 相等");        }else{            NSLog(@"subStr1 和 subStr2 不相等");        }

    //比较字符串大小

        NSString *string12 = @"yanshuxin";        NSString *string13 = @"Hello";        NSComparisonResult result = [string12 compare:string13];        switch (result) {            case NSOrderedAscending:                NSLog(@"string12 < string13");                break;            case NSOrderedSame:                NSLog(@"string12 = string13");                break;            case NSOrderedDescending:                NSLog(@"string12 > string13");                break;            default:                break;        }  

    //根据字符串拿到对应的range

        NSRange strRange = [string11 rangeOfString:@"你看"];        NSLog(@"strRange = %@",[NSValue valueWithRange:strRange]);        NSRange strRange1 = [string11 rangeOfString:@"你"];        NSLog(@"strRange1 = %@",[NSValue valueWithRange:strRange1]);        //找到第一个就不找了 

    //判断字符串中是否有XX前缀或XX后缀

        NSString *string14 = @"www.baidu.com";        if ([string14 hasPrefix:@"http://"]) {            NSLog(@"含有此前缀");        }else{            NSLog(@"无此前缀");        }        NSString *string15 = @"asdf.jpg";        if ([string15 hasSuffix:@".jpg"] || [string15 hasSuffix:@".png"]) {            NSLog(@"含有此后缀");        }

    //字符串拼接

        NSString *connStr = [@"http://" stringByAppendingString:string14];        NSLog(@"connStr = %@",connStr);        NSString *domainStr = @"http://wechat.palm-h.com";        NSString *xxx = @"login";        //http://wechat.palm-h.com/login        NSString *string16 = [NSString stringWithFormat:@"%@/%@",domainStr,xxx];        NSLog(@"string16 = %@",string16);        NSString *string17 = [domainStr stringByAppendingPathComponent:xxx];        NSLog(@"string17 = %@",string17);        //http://web.52pk.com/uploads/141017/30_105806_1_lit.jpg        NSString *imgPath = @"http://web.52pk.com/uploads/141017/30_105806_1_lit.jpg";        imgPath = [imgPath lastPathComponent];//获取路径的最后一段        NSLog(@"imgPath = %@",imgPath);        path = [path lastPathComponent];        NSLog(@"path = %@",path);        NSString *theImageName = @"yanshuxin";        theImageName = [theImageName stringByAppendingPathExtension:@"png"];        NSLog(@"theImageName = %@",theImageName);   

    //uppercaseString:把所有字母转换为大写    //lowercaseString:把所有字母转换为小写    //capitalizedString:每个单词的首字母转换为大写

        NSString *str1 = @"I lovE kongfu";        NSLog(@"%@ \n %@ \n %@",[str1 uppercaseString],[str1 lowercaseString],[str1 capitalizedString]);

    //不可变字符串:单个内容替换

        stringByReplacingOccurrencesOfString        NSString *aa = [theImageName stringByReplacingOccurrencesOfString:@"y" withString:@"Y"];        NSLog(@"%@",aa);

    //不可变字符串:指定长度内容替换

        stringByReplacingCharactersInRange        NSString *aaa = [theImageName stringByReplacingCharactersInRange:NSMakeRange(1, 3) withString:@"ANS"];        NSLog(@"%@",aaa);

    //不可变字符串:将原字符串的内容进行分割,分割得到的结果放到一个数组里,作为返回值.

        NSString *bb = @"yan,shu,xin";        NSArray *ary = [bb componentsSeparatedByString:@","];        for (int tmp = 0; tmp < 3; tmp++) {            NSLog(@"%@",ary[tmp]);        }