字符串  又是字符串 总结了,不谢 // 创建字符串- (void)CreatString{    // <1> 创建字符创    NSString *strS = @"This is a String!";        // <2> 创建空字符串,给予赋值    NSString *strK = [[NSString alloc] init];        strK = @"This is a String!";        NSLog(@"strS:%@, strK%@",strS,strK);        // <3> 使用变量初始化字符串    NSString *name = @"aofe";        NSString *strN = [NSString stringWithFormat:@"My name is %@",name];        NSLog(@"strN:%@",strN);}// 判断是否包含某字符串- (void)IsContainsString{    NSString *str1 = @"NSStringInformation.txt";        // <1> 检查字符串是否以另一个字符串开头    [str1 hasPrefix:@"NSString"] == 1? NSLog(@"YES") :NSLog(@"NO");        // <2> 检查字符串是否以另一个字符串结尾    [str1 hasSuffix:@".txt"] == 1? NSLog(@"YES") :NSLog(@"NO");        // <3> 检查字符串是否包含其他字符串    [str1 rangeOfString:@"Information"].length > 0 ? NSLog(@"YES") :NSLog(@"NO");    }// 读写字符串-(void)WriteAndReadString{    // 文件路径    NSString *path = @"wenJianQuanLuJing";        // <1> 从文件读取字符串    NSString *strW = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:NULL];        // <2> 将字符串写入到文件    [strW writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:NULL];}// 比较两个字符串-(void)ComparerTwoString{    NSString *str1 = @"This is String1";        NSString *str2 = @"THIS is String2";        // 比较两个字符串是否相等    BOOL result1 = [str1 isEqualToString:str2];        // 比较两个字符串(comparer方法返回三种值:NSOrderedAscending = -1L, NSOrderedSame, NSOrderedDescending)        NSComparisonResult result2 = [str1 compare:str2];        // 不考虑大小比较字符串    NSComparisonResult result3 = [str1 caseInsensitiveCompare:str2];        NSLog(@"result1:%d,result2:%ld,result3:%ld",result1,(long)result2,(long)result3);    }// 改变字符串的大小写-(void)ChangeStringCase{    NSString *str1 = @"this is string1";    NSString *str2 = @"THIS IS STRING2";        // 全部大写    [str1 uppercaseString];        // 全部小写    [str2 lowercaseString];        // 首字母大写    [str1 capitalizedString];}// 在字符串中搜索子串-(void)SearchString{    NSString *str1 = @"This is String1";    NSString *str2 = @"is";        NSRange range = [str1 rangeOfString:str2];        NSLog(@"location:%lu,length:%lu",(unsigned long)range.location,(unsigned long)          range.length);    }// 替换字符串-(void)ReplaceString{    NSString *strL = @"hello china";        NSString *strN = [strL stringByReplacingOccurrencesOfString:@"china" withString:@"beijing"];        NSLog(@"strL:%@,strN:%@",strL,strN);}// 分隔字符串成数组-(void)ComponentsString{    NSString *str = @"a b c d e";    // 以空格分隔字符串成数组    NSArray *arr = [str componentsSeparatedByString:@" "];        NSLog(@"arr:%@,arr.count:%lu",arr,(unsigned long)arr.count);    }// 数组拼接成字符串-(void)ArrayToString{    NSArray *array = [NSArray arrayWithObjects:@"this",@"is",@"String", nil];    // 用空格隔开数组中的元素    NSString *str = [array componentsJoinedByString:@" "];        NSLog(@"str:%@",str);}// 从字符串中抽取出新的字符串-(void)DrawNewString{    NSString *str = @"This is String";    // 从字符串的开头一直截取到指定位置,但不包括该位置的字符.    NSString *str1 = [str substringToIndex:5];        // 从指定位置开始(包括自定位置的字符串)一直到最后    NSString *str2 = [str substringFromIndex:5];        // 按照所给定的位置和长度,任意的从字符串中截取新的字符串    NSString *str3 = [str substringWithRange:NSMakeRange(4, 5)];        NSLog(@"str1:%@,str2:%@,str3:%@",str1,str2,str3);}// 可变字符串的操作- (void)NSMutableStringOperation{    // 给字符串分配容量    NSMutableString *strM = [NSMutableString stringWithCapacity:100];    NSLog(@"strM:%@",strM);        // 在已有的字符串后面添加字符串    NSMutableString *strM1 = [[NSMutableString alloc] initWithString:@"This is a"];    NSLog(@"strM1:%@",strM1);        [strM1 appendString:@"NSMutableString"];    NSLog(@"strM1:%@",strM1);        // 在已有字符串中按照所给出的范围和长度删除字符    [strM1 deleteCharactersInRange:NSMakeRange(0, 5)];    NSLog(@"strM1:%@",strM1);        // 在字符串指定位置插入字符串    [strM1 insertString:@"Hello" atIndex:0];    NSLog(@"strM1:%@",strM1);        // 将已有字符串替换成其他字符串    [strM1 setString:@"Hello World"];    NSLog(@"strM1:%@",strM1);        // 按照所给出的范围,用新字符串替换原来的字符串    [strM1 replaceCharactersInRange:NSMakeRange(0, 5) withString:@"Hi"];    NSLog(@"strM1:%@",strM1);}// 时间操作- (void)NSDateOperation{    // 得到当前日期    NSDate *date1 = [NSDate date];    NSLog(@"date:%@",date1);        NSDate *date2 = [NSDate dateWithTimeIntervalSinceNow:3];        // 比较日期:        // <1> 比较日期是否相同    BOOL result =[date1 isEqualToDate:date2];        // <2> 比较日期 返回时间较早的日期    NSDate *dateE = [date1 earlierDate:date2];        // <3> 比较日期 返回时间较晚的日期    NSDate *dateL = [date1 laterDate:date2];        NSLog(@"result:%d, dateE:%@, dateL:%@",result,dateE,dateL);        // 设置日期的格式    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];        // 设置几种默认的显示效果    [formatter setTimeStyle:NSDateFormatterMediumStyle];        //自定义日期显示效果    [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];        NSString *time = [formatter stringFromDate:date1];        NSLog(@"%@",time);    }