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一.不可变字符串 1.追加字符串: [newStr stringByAppendingFormat:@"%C",c]; 2.字符串分割方法: [NSString componentsSeparatedByString:@"\n"]; 3.字符串提取: unichar c = [string characterAtIndex:i];提取第i个元素,返回值为unichar [string substringToIndex:3]; 从头提取到索引 [string substringFromIndex:3];从索引提取到结束 [string substringWithRange:NSMakeRange(0, 4)];指定范围提取 4.读取文件的标准格式: NSString *content = [NSString stringWithContentsOfFile:PATH encoding:NSUTF8StringEncoding error:nil]; 5.创建格式化字符串:占位符 NSString * string = [[NSString alloc] initWithFormat:@”I am %d”,age]]; 6.C字符串变oc: [NSString stringWithUTF8String:buff]; 7.比较字符串: [string1 compare:string2];返回值为-1 0 1 不考虑大小写比较字符串 [string caseInsensitiveCompare:string02]; 8.大小写转化: 1.[string uppercaseString] 小写转大写 2.[string lowercaseString] 大写转小写 3.[string capitalizedString] 单词首字母大写 其余小写,其他字符保持不变 9.搜索子串: NSRange range = [string1 rangeOfString:string2]; //NSRange代表一个范围:子串string2 在长串string1中的范围(位置和长度) NSMakeRange(location,length)创建一个range结构体类型 10.判断前后缀: [String1 hasPrefix:@"NSString”]返回值BOOL型 [String1 hasSuffix:@".txt"] 11.分割: [string componentsSeparatedByString:@“@“];//分割字符串返回值是不可变数组类型 二.可变字符串 1.追加字符串: [mutableString1 appendString:] [mutableString1 appendFormat:] 2.指定位置插入字符串: [mutableString1 insertString:@"Hi! " atIndex:0]; 3.在指定范围内删除字符串 [mutableString1 deleteCharactersInRange:NSMakeRange(0, 5)]; 4.修改字符串 [mutableString1 setString:@"Hello Word!"]; 5.替换: [mutableString1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"]; 三.不可变数组: 1.获取数组元素 [arr objectAtIndex:1]; 也可以写成arr[1]; 2.拼接: [arr componentsJoinedByString:@“\n”];返回值为字符串 3.查询: [arr containsObject:(id)];返回值为Bool 如果数组arr中有索引返回YES,没有返回NO 四.可变数组: 1.交换 [mutableArr exchangeObjectAtIndex:i withObjectAtIndex:i+1]; 2.增加 [mutableArr addobject:@“four”]; 3.在指定位置插入一个元素 [mutableArr addObject:@"four"]; 4.删除 [mutableArr removeAllObjects]; [mutableArr removeObject:@"one"]; [mutableArr removeObjectAtIndex:0]; 5.修改指定索引的元素 [mutableArr replaceObjectAtIndex:1 withObject:@"二"]; 6.排序 [mutableArr sortUsingSelector:@selector(排序准则方法名)]; 五.不可变可变字典 1.创建字典 NSDictionary *dict = [[NSDictionary alloc] initWithObjectsAndKeys:@"1",@"one",@"2",@"two",@"3",@"three",@"4",@"four", nil];//一个value对应一个key 用一个字典初始化一个新的字典 NSDictionary * dict2 = [[NSDictionary alloc] initWithDictionary:dict] 2.用两个数组实例化一个字典对象,两个数组元素要对应成键值对 NSArray *keys = [NSArray arrayWithObjects:@"one",@"two", nil]; NSArray *values = [NSArray arrayWithObjects:@"1",@"2", nil]; [NSDictionary dictionaryWithObjects:values forKeys:keys]; 3.获取所有的值 NSArray *newValues = [dict allValues]; 4.获取字典所有的key NSArray *newKeys = [dict allKeys]; 5.根据key 找到相应的值 NSString *str = [dict objectForKey:@"three"]; 也可以写成dict[@“three”] 六.可变字典 1.增改: [mDict setObject:@"111" forKey:@"XXX"];//当key不存的时候表示增加键值对 [mDict setObject:@"111" forKey:@"one"];//当key存在的时候表示修改键值对 2.删除 删除指定的键值对: [mDict removeObjectForKey:@"XXX"]; 删除所有键值对 [mDict removeAllObjects];