////  main.m//  NSString/**    NSString    1.NSString 是一个不可以变的字符串对象    2.NSMutableString是一个可变字符串。 　　下面代码为字符串的：增、删、替换、查方法得演示。  */#import 
     
      void MutableNSString(){    NSMutableString *mutableString  =[NSMutableString stringWithFormat:@"我是可变字符串"];    //指定位置增加字符串    [mutableString insertString:@"增加" atIndex:([mutableString length])];    NSLog(@"%@",mutableString);        //指定范围替换全部字符串    [mutableString replaceCharactersInRange:NSMakeRange(0, [mutableString length]) withString:@"替换后得字符串"];    NSLog(@"%@",mutableString);    NSRange rang  = [mutableString rangeOfString:@"字符串"];    [mutableString replaceCharactersInRange:rang withString:@"string"];    NSLog(@"%@",mutableString);    //重新设置可变字符串内容    [mutableString setString:@"ABCDAa"];    //将A替换成E，方式为区分大小    [mutableString replaceOccurrencesOfString:@"A" withString:@"E" options:NSLiteralSearch range:NSMakeRange(0, [mutableString length])];    NSLog(@"%@",mutableString);    //删除指定范围得字符串    NSRange deleteRang =  [mutableString rangeOfString:@"a"];    //删除前最好判断是否存在,或者使用@try捕捉异常    [mutableString deleteCharactersInRange:deleteRang];        NSLog(@"%@",mutableString);}void BaseStringMeth(){    //字符串的基本方法    NSString *str1  =  @"hello NSString ";    //查询字符串得长度    NSUInteger length=  [str1 length];    NSLog(@"length = %lu",length);    // 转换大写    NSString *upperNSString = [str1 uppercaseString];    NSLog(@"%@",upperNSString);    //转换小写    NSString *lowerNSString = [str1 lowercaseString];    NSLog(@"%@",lowerNSString);    //字符换链接    NSString *appendString  = @"study ";    NSString *afterAppendString = [appendString stringByAppendingString:str1];    NSLog(@"%@",afterAppendString);    //判断字符串是否相等    NSString *a = @"string a";    NSString *b = @"string b";    NSString *c = @"string a";    NSString *d = @"String a";    NSString *e = @"Strina a";    if([a isEqualToString:b] != YES){        NSLog(@"不相等");    }    if([a isEqualToString:c]){        NSLog(@"相等");    }    // 这个判断是严格区分大小写    if([a isEqualToString:d]){        NSLog(@"相等");    }    //字符串比较大小，字符串得比较其实就是比较    NSString *compare1= @"1";    NSString *compare2 = @"2";    //- (NSComparisonResult)compare:(NSString *)string; 比较方法返回值是NSComparisonResult,他是一个枚举类型    //typedef NS_ENUM(NSInteger, NSComparisonResult) {NSOrderedAscending = -1L, NSOrderedSame, NSOrderedDescending};    if([compare1 compare:compare2] == NSOrderedAscending ){        NSLog(@"compare1 
      
       compare2");    }        NSString *compare3= @"res1";    NSString *compare4 = @"RES1";    if([compare3 compare:compare4] == NSOrderedAscending ){        NSLog(@"compare3 
       
        compare4");    }    //忽略大小写的比较    if([compare3 caseInsensitiveCompare:compare4] == NSOrderedAscending ){        NSLog(@"compare3 
        
         compare4");    }        }void NSStringSearch(){    //字符串的查找    NSString *str1  =  @"hello NSString ";    NSString *hello = @"hello";    //查找hello字符串的位置    NSRange helloRang = [str1 rangeOfString:hello];    NSLog(@"hello location=%lu and length=%lu",helloRang.location,helloRang.length);        NSString *hello2 = @"hello2";    NSRange helloRang2 = [str1 rangeOfString:hello2];    //找不到对应的字符串的时候系统会返回一个NSNotFound    if(helloRang2.location  == NSNotFound){        NSLog(@"在%@,中没有找到对应的字符串%@",str1,hello2);    }    /**     传入 NSStringCompareOptions 枚举的值     enum{     NSCaseInsensitiveSearch = 1,//不区分大小写比较     NSLiteralSearch = 2,//区分大小写比较     NSBackwardsSearch = 4,//从字符串末尾开始搜索     NSAnchoredSearch = 8,//搜索限制范围的字符串     NSNumbericSearch = 64//按照字符串里的数字为依据，算出顺序。例如 Foo2.txt < Foo7.txt < Foo25.txt     //以下定义高于 mac os 10.5 或者高于 iphone 2.0 可用     NSDiacriticInsensitiveSearch = 128,//忽略 "-" 符号的比较     NSWidthInsensitiveSearch = 256,//忽略字符串的长度，比较出结果     NSForcedOrderingSearch = 512//忽略不区分大小写比较的选项，并强制返回 NSOrderedAscending 或者 NSOrderedDescending     //以下定义高于 iphone 3.2 可用     NSRegularExpressionSearch = 1024//只能应用于 rangeOfString:..., stringByReplacingOccurrencesOfString:...和 replaceOccurrencesOfString:... 方法。使用通用兼容的比较方法，如果设置此项，可以去掉 NSCaseInsensitiveSearch 和 NSAnchoredSearch     }          */    //指定范围进行查找。我们可以通过options来确定查询得方式。从头开始还是从尾开始    NSRange nsstringRang= [str1 rangeOfString:@"NSString" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [str1 length])];    NSLog(@"location=%lu,length=%lu",nsstringRang.location,nsstringRang.length);        }//字符串的截取void SubString(){    //字符串截取    NSString *str1  =  @"hello NSString ";        //从第5个字符开始截取到最后    NSString *subString = [str1 substringFromIndex:5];    NSLog(@"%@",subString);//输出NSString    NSRange rang = {
   0,5};    //指定范围得截取    NSString *subByRang = [str1 substringWithRange:rang];    NSLog(@"%@",subByRang);//输出hello    //从0开始截取到指定的位置    NSString *subToPosition= [str1 substringToIndex:5];    NSLog(@"%@",subToPosition);//输出hello}//字符串的创建void CreateNSString(){    //字符串的创建    NSString *str1 = @"hello NSString ";    //静态方法创建字符串,    NSString *str2 = [NSString stringWithFormat:@"NSString%i",2];    //动态创建字符串,由于动态创建计数器会+1因此我们需要自己释放，str3初始化时没有相应的值    NSString *str3 = [[NSString alloc]init];        NSLog(@"%@",str3);    [str3 release];    }int main(int argc, const char * argv[]) {    @autoreleasepool {        CreateNSString();        BaseStringMeth();        SubString();        NSStringSearch;        MutableNSString();    }    return 0;}