1.NSString,NSArray,NSDictionary的基本用法

1.NSString

NSString *string1 = @"字面量";//--->字符串常量//创建一个空的字符串NSString *string2 = [[NSString alloc] init];NSString *string3 = [NSString string];//快速创建一个字符串  常量区NSString *string4 = [[NSString alloc] initWithString:@"abc"];NSString *string5 = [NSString stringWithString:@"xyz"];//创建一个格式化的字符串  堆区NSString *string6 = [[NSString alloc] initWithFormat:@"整数:%d",10];NSString *string7 = [NSString stringWithFormat:@"浮点数:%g",3.14];//--->判断字符串内容是否相同BOOL isEqual = [string4 isEqualTo:string5];if (string4 == string5) {    NSLog(@"same point");//--->判断地址是否相同}//字符串比较大小{NSOrderedAscending = -1L, NSOrderedSame, NSOrderedDescending};NSComparisonResult result = [string4 caseInsensitiveCompare:string5];[string4 length];//--->求字符串长度[string4 uppercaseString];//全部大写;lowercaseString(全小写);capitalizedString(首字母大写)//--->字符串转换成基本数据类型NSString *string8 = @"3.14";float pi = [string8 floatValue];//字符串转换成数组NSString *string9 = @"abc bcd iOS";NSArray *array = [string9 componentsSeparatedByString:@" "];//截取字符串-->substringFromIndex;substringToIndex[string9 substringWithRange:NSMakeRange(4, 3)];//--->bcd//字符串拼接 str123--->abcxyzNSString *str1 = [NSString stringWithFormat:@"%@%@",string4,string5];NSString *str2 = [string4 stringByAppendingFormat:@"%@",string5];NSString *str3 = [string4 stringByAppendingString:string5];//查找字符串NSString *link = @"abcdefg-yun-nihao";NSRange range = [link rangeOfString:@"-yun-"];NSLog(@"%@",NSStringFromRange(range));//--->{7, 5}NSMutableString *str = [[NSMutableString alloc] initWithString:@"abc"];[str insertString:@"...xyz" atIndex:3];//--->abc...xyz[str replaceCharactersInRange:NSMakeRange(0, 3) withString:@"efg"];//--->efg...xyz[str deleteCharactersInRange:NSMakeRange(0, 3)];//--->...xyz

2.NSArray

NSArray *ar = [NSArray array];//初始化一个空数组NSArray *arr = @[@"123",@123,@"hello"];NSArray *arr1 = [NSArray arrayWithObjects:@"123",@123,@"hello", nil];NSMutableArray *arr2 = [NSMutableArray arrayWithObjects:@"123",@123,@"hello", nil];NSLog(@"%d",[arr1 containsObject:@"123"]);//包含对象//快速枚举:能快速的遍历数组等容器对象,对容器里面的每一个元素便利//为了增加代码的可读性,尽量让forin前面的部分类型和数组里的元素类型相同for (NSArray *temp in arr1) {    NSLog(@"%@",temp);}

3.NSDictionary

//常见初始化方法NSDictionary *di = [NSDictionary dictionary];NSDictionary *dic = @{@"age":@"22",@"name":@"zhangsan"};//key-->valueNSDictionary *dic1 = [NSDictionary dictionaryWithObjectsAndKeys:@"22",@"age",@"zhangsan",@"name", nil];//value-->keyNSMutableDictionary *dic2 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"22",@"age",@"zhangsan",@"name", nil];//1.key是唯一的且不能为空,但是value可以重复//2.当key不存在时是进行键值对的添加,存在时是对value的修改(针对可变字典)//3.setObject是字典自己的方法,setValues是KVC的方法,即使效果一样,但是对字典还是用setObject[dic2 setObject:@"500235" forKey:@"id"];NSLog(@"%@",[dic1 allValues]);//所有的值NSLog(@"%@",dic1.allKeys);//所有的键NSLog(@"%@",[dic1 objectForKey:@"name"]);//通过键取值NSLog(@"%@",dic1[@"name"]);//dic[对应的key]-->语法糖//遍历所有的valuesfor (int i = 0; i < dic1.count; i++) {    NSLog(@"%@",dic1.allValues[i]);}//forin的前部分是字典里的keyfor (NSString *str in dic1) {    NSLog(@"%@",str);//所有key    NSLog(@"%@",dic1[str]);//所有value}