学步园

//NSString 操作均不改变自身值<br /> //构建字符串<br /> NSString *szTmp = @"A string"; //直接赋值<br /> szTmp = nil;</p> <p> int n = 5;<br /> NSString *szMyString = [NSString stringWithFormat:@"The number is %d",n]; //The number is 5<br /> [szMyString stringByAppendingFormat:@"%d",22]; //附加字符串返回值：The number is 522<br /> //但是szMyString本身并没有改变，其值依然：The number is 5

//长度与索引字符<br /> NSLog(@"%d",szMyString.length); //字符串长度：15<br /> NSLog(@"%c",[szMyString characterAtIndex:2]); //返回字符:e<br />

//与c字符串相互转换<br /> printf("%s\n",[szMyString UTF8String]); //转为__strong const char *<br /> const char *szTmp1 = [szMyString cStringUsingEncoding:NSUTF8StringEncoding];<br /> printf("%s\n",szTmp1); //转为__strong const char *</p> <p> NSLog(@"%@",[NSString stringWithCString:szTmp1 encoding:NSUTF8StringEncoding]); //转为nsstring<br />

//字符串写文件<br /> NSError *error;<br /> NSString *szPath = [NSHomeDirectory() //应用程序沙盒路径<br /> stringByAppendingPathComponent:@"Documents/testFile.txt"]; //附加路径地址<br /> if (![szMyString writeToFile:szPath atomically:YES //atomically:是否是原子访问文件的<br /> encoding:NSUTF8StringEncoding error:&error]) { //写入成功返回yes 否则no<br /> NSLog(@"Error writing to file :%@",[error localizedDescription]); //输出错误描述<br /> return 1;<br /> }<br /> NSLog(@"File write success");<br />

//文件读字符串<br /> NSString *szInString = [NSString stringWithContentsOfFile:szPath //读取文件信息<br /> encoding:NSUTF8StringEncoding error:&error];<br /> if (!szInString)<br /> {<br /> //失败<br /> }<br /> NSLog(@"%@",szInString); //成功<br />

//字符串转为数组<br /> NSArray *arrayWord = [szMyString componentsSeparatedByString:@" "]; //有空格的拆分为单词保存<br /> NSLog(@"%@",arrayWord);<br />

//索引子串<br /> NSString *szSub1 = [szMyString substringToIndex:3]; //0－2,前3个:The<br /> NSLog(@"%@",szSub1);</p> <p> NSString *szSub2 = [szMyString substringFromIndex:4]; //4－尾，去掉前4个:number is 5<br /> NSLog(@"%@",szSub2);<br />

//范围索引<br /> NSRange range;<br /> range.location = 4; //从4开始<br /> range.length = 6; //6个字符<br /> NSString *szSub3 = [szMyString substringWithRange:range]; //number<br /> NSLog(@"%@",szSub3);<br />

//搜索与替换<br /> NSRange rangeSearch = [szMyString rangeOfString:@"is 5"]; //搜索<br /> if (rangeSearch.location != NSNotFound) { //搜索不到是 NSNotFound<br /> //成功：rangeSearch.location;//位置 rangeSearch.length;//长度<br /> }</p> <p> NSLog(@"%@",[szMyString stringByReplacingCharactersInRange:rangeSearch //用位置匹配替换<br /> withString:@"isn't 10"]);</p> <p> NSString *szReplaced = [szMyString stringByReplacingOccurrencesOfString:@" " withString:@"*"]; //匹配字符串替换<br /> NSLog(@"%@",szReplaced);<br />

//改变大小写<br /> NSLog(@"%@",[szMyString uppercaseString]); //大写<br /> NSLog(@"%@",[szMyString lowercaseString]); //小写<br /> NSLog(@"%@",[szMyString capitalizedString]); //首字母大写<br />

//比较字符串<br /> NSString *sz1 = @"Hello World!";<br /> NSString *sz2 = @"Hello Mom!";<br /> if ([sz1 isEqualToString:sz2]) {/*相等*/}<br /> if ([sz1 hasPrefix:@"Hello"]) {NSLog(@"前部分相等");} //从头开始比较<br /> if ([sz1 hasSuffix:@"d!"]) {NSLog(@"后部分相等");} //从尾部比较<br />

//字符串转换数字<br /> NSString *szNumber = @"3.14";<br /> [szNumber intValue];<br /> [szNumber boolValue];<br /> [szNumber floatValue];<br /> [szNumber doubleValue];<br />

//可变字符串<br /> NSMutableString *szMuMyString = [NSMutableString stringWithString:@"Hello"];<br /> [szMuMyString appendFormat:@"World"]; //字符串，改变自身<br /> [szMuMyString uppercaseString];<br /> NSLog(@"%@",szMuMyString);<br />