// 首字母大写

    NSString *string = @"liupengfei";

    NSLog(@"\n function: %s \n string: %@",__FUNCTION__,[string capitalizedString]);

 // 分割字符串

    NSString *string1 = @"I am iOS Engineer";

    NSArray *array = [string1 componentsSeparatedByString:@"iOS"];

    NSLog(@"\n function: %s \n array: %@",__FUNCTION__,array);

    NSString *str1 = [array objectAtIndex:0];

    NSString *str2 = [array objectAtIndex:1];

    NSLog(@"\n function: %s \n str1: %@ \n str2: %@", __FUNCTION__,str1, str2);

 

// 追加字符串

    NSMutableString *muStr = [[NSMutableString alloc] initWithString:@"I Love "];

    [muStr appendString:@"iOS"];

    NSLog(@"\n function: %s \n muStr: %@", __FUNCTION__,muStr);

 

 // 插入字符串

    NSMutableString *muString = [[NSMutableString alloc] initWithString:@"I  iOS"];

    [muString insertString:@"Love" atIndex:2];

    NSLog(@"\n function: %s \n muString: %@", __FUNCTION__,muString);

 

// 删除字符串

    NSMutableString *muString1 = [[NSMutableString alloc] initWithString:@"I Love iOS"];

    [muString1 deleteCharactersInRange:NSMakeRange(2, 4)];

    NSLog(@"\n function: %s \n muString1: %@", __FUNCTION__, muString1);

 

// 判断是否包含前后缀

    NSMutableString *muString2 = [[NSMutableString alloc] initWithString:@"I Love iOS"];

    BOOL isHasI = [muString2 hasPrefix:@"I"];

    BOOL isHasA = [muString2 hasPrefix:@"A"];

    NSLog(@"\n function: %s \n isHasI: %d \n isHasA: %d", __FUNCTION__,isHasI,isHasA);

 

// 替换字符串

    NSMutableString *muString3 = [[NSMutableString alloc] initWithString:@"I Love iOS"];

    NSString *replaceString = [muString3 stringByReplacingOccurrencesOfString:@"Love" withString:@"Hit"];

    NSLog(@"\n function: %s \n replaceString: %@", __FUNCTION__,replaceString);

 

 

// 去除字符串首尾的空格和换行符

    NSString *string = @" I Love iOS ";

    NSString *text = [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

    NSLog(@"\n function: %s \n text:%@", __FUNCTION__,text);