object-c 学习之Foundation Kit

        /*--------------通过格式字符串和参数创建字符串--------------*/</span>                NSString *height = nil;        height = [NSString stringWithFormat:@"The height is %d",4];        //把height输出        NSLog(@"%@",height);                 /*----取字符串的长度-----*/        NSInteger length = [height length];        NSLog(@"%ld",(long)length);         /*--------字符串比较-------*/        NSString *firstName = @"power Node 100";        NSString *anotherName = [NSString stringWithFormat:@"Power Node %d",50];        //isEquaito 返回一个Bool值来表示两个字符串的内容是否相同（相等）        if ([firstName isEqualTo:anotherName]) {            NSLog(@"They are the same");        }                //两个字符串的比较        NSString *str1 = @"helloworld";        NSString *str2 = @"hellowrold";        BOOL result1 = ([str1 compare:str2] == NSOrderedSame);        NSLog(@"result1 is %d",result1);                //按字母顺序进行比较        BOOL result2 = ([str1 compare:str2] == NSOrderedAscending);        NSLog(@"result1 is %d",result2);        BOOL result3 = ([str1 compare:str2] == NSOrderedDescending);        NSLog(@"result1 is %d",result3);        //        if (result1 == -1) {//            NSLog(@"str1小于str2")；//        }//        if (result1 == 1) {//            NSLog(@"str1大于str2")；//        }                 /*--------创建可变字符串-------*/                NSMutableString *str3 = [NSMutableString stringWithCapacity:20];        NSMutableString *str4 = [NSMutableString stringWithFormat:@"我今年%d岁",29];         //往可变字符串末尾追加字符        [str3 appendString:@"Hello,"];           //在末尾加字符串；        [str3 appendFormat:@"我是zhan%d",3];      //与stringWithFormat类似，按照格式化字符添加到末尾                [str3 appendString:str4];                //把str4 的内容追加到str3的末尾        NSLog(@"%@",str3);                /*--------创建可变字符串-------*/                NSMutableString *friend = [NSMutableString stringWithCapacity:50];        [friend appendString:@"zhangsan lisi wangwu zhaoliu"];                NSRange range = [friend rangeOfString:@"wangwu"];        //range.length++ ;   //把wangwu后面的空格删掉        [friend deleteCharactersInRange:range];        NSLog(@"%@",friend);                /*--------改变字符串的大小写-------*/        NSString *string11 = @"ASreing";        NSString *string12 = @"String";        NSLog(@"after uppercase srting11:%@",[string11 uppercaseString]);        NSLog(@"after lowercase string12:%@",[string12 lowercaseString]);        NSLog(@"capitalized string11:%@",[string11 capitalizedString]);                        /*--------字符串中是否还包含别的字符串-------*/                NSString *fileName = @"draft-chapter.pages";        if ([fileName hasPrefix:@"draft"]) {            NSLog(@"This is a draft");        }        if ([fileName hasSuffix:@".mov"]) {            NSLog(@"This is a mov");        }                        //-substringFromIndex:从字符串的指定的位置开始(包括位置的字符) 截取        NSString *string1 = @"This is a string";        NSString *string2 = [string1 substringFromIndex:3];        NSLog(@"%@",string2);        //-substringToindex：从字符串的开头一直截取到指定的位置(但不包括指定位置的字符)        NSString *string3 = [string1 substringToIndex:5];        NSLog(@"%@",string3);        //-substringWithRange:按照range给出的位置和长度来截取子串；        NSString *string4 =[string1 substringWithRange:NSMakeRange(0, 6)];        NSLog(@"%@",string4);                        /*--------创建一个数组-------*/        NSArray *arr1 = @[@"zhangsan",@"lisi",@"wangwu",@"zhaoliu"];        // NSArray *arr2 = [NSArray arrayWithObjects:@"zhangsan",@"lisi",@"wangwu",@"zhaoliu",nil];                NSLog(@"%@",arr1);   //类似与c语言的格式        //取对应下标的元素//        NSString *string10 = [arr1 objectAtIndex:2];//        NSLog(@"%@",str);        NSLog(@"%@",arr1[2]);                //数组个数                NSLog(@"The item of arr1 is :%lu",(unsigned long)[arr1 count]);                 /*--------创建一个可变数组，并从中删除指定对象-------*/        NSMutableArray *arr3 = [NSMutableArray arrayWithCapacity:12];        [arr3 addObject:@"one"];        [arr3 addObject:@"Two"];        [arr3 addObject:@"Three"];        NSLog(@"The element of arr3 is :%@",arr3);                        //从可变数组中删除对象        [arr3 removeObject:@"one"];  //删除指定对象        [arr3 removeObjectAtIndex:0];   //删除下标        NSLog(@"The element of arr3 is :%@",arr3);                        [arr3 addObjectsFromArray:arr1];           //把数组arr1追加到arr3        NSLog(@"The element of arr3 is :%@",arr3);        [arr3 insertObject:@"insert" atIndex:0];   //在指定位置为arr3添加对象        NSLog(@"The element of arr3 is :%@",arr3);                //数组的遍历                NSInteger counter = [arr3 count];        for (int i = 0; i < counter; i++) {//            NSString *string11 = arr3[i];            NSString *string11 = [arr3 objectAtIndex:i];            NSLog(@"The element of arr3 is :%@",string11);                  }                /*--------对路径和文件名进行扩展-------*/        NSString *path = @"~/hello.txt";        NSString *absolutePath = [path stringByExpandingTildeInPath];        NSLog(@"absolutepath:%@",absolutePath);        NSString *tem = [absolutePath stringByAbbreviatingWithTildeInPath];        NSLog(@"%@",tem);                /*--------快速枚举-------*/                for (NSString *enum1 in arr1) {            NSLog(@"arr1:%@",enum1);        }