(本文参考资料整理，仅作为初学笔记)

一，字符串

1.字符串字面量

NSString *a＝@"this is a";

2.字符串对象初始化

NSString *aString = [[NSString alloc] initWithString:@"some string literal"];//(分配内存并初始化方法）

NSString *aString = [NSString stringWithString:@"some string literal"];（便捷方法）

3.格式化字符串

int value=3;

NSString *aString = [NSString stringWithFormat:@ "value is %d",value];

(补充：int(32位)－％d，unsigned int－％u，long(32位或64位)－%ld,unsigned long-%lu,float-%f,NSObject子类实例-%@)

4.对象格式说明符

NSString *aString=@"criminals";

NSString *anotherString = [NSString stringWithFormat :@"When you %@ strings,only %@ will use strings. ",@"criminalize",aString];

5.字符串比较

NSString *a=@"hello";

NSString *b=@"hello";

BOOL stringsAreEqual=([a isEqualToString:b]);

二，数字

NSNumber的使用

NSNumber *aNumber = [NSNumber numberWithInt:3];

NSLog(@"I have %@ apples",aNumber);

NSLog(@"I have %d apples",[aNumber intValue]);

三，数组

1.创建NSArray对象示例

NSArray *emptyArray = [NSArray array];

NSArray *firstList=[NSArray arrayWithObjects:@"apple","bananas","milk",nil];

NSArray *secList=[[NSArray alloc] initWithObjects:@"apples",@"bananas",@"milk",nil];

NSArray *thirdList=[NSArray arrayWithArray:secList];

2.数组字面语法

NSArray *array = @[@"hello",NSApp,[NSNumber numberWithInt:3]];

3.异构数组

NSArray *array=[NSArray arrayWithObjects:@"a string",[NSNumber numberWithBool:YES],nil];

4.数组下标

NSString *str=myArray[3];

四，集合

1.集合的声明

NSSet *set=[NSSet setWithObjects:@"apples",@"milk",@"bananas"];

2.测试对象是否包含在集合中

NSSet *set=[NSSet setWithObjects:@"apples",@"milk",@"bananas"];//集合的声明

NSString *string=@"apples";

if([set containsObject:string])//测试对象是否包含在集合中

NSLog(@"YES!");

NSArray *array=[set allObjects];//赋值给数组

for(NSString *string in array){//遍历数组

NSLog(@"%@",string);

}

3.可变集合

NSMutableSet *mutableSet=[NSMutableSet setWithObjects:@"apple",@"bananas",@"milk",nil];//声明可变数组

[mutableSet intersectSet:[NSSet setWithObject:@"apple"]];//现在只有"apples"了

[mutableSet uniontSet:[NSSet setWithObject:@"apple",@"bread",@"jam",nil]];//现在有"apple"，"bread"，"jam"

[mutableSet minusSet:[NSSet setWithObject:@"bread"]];//现在有"apple","jam"

[mutableSet minusSet:[NSSet setWithObject:@"pasta"]];//没有变化

五，字典

1.使用字典

NSArray *keys=[NSArray arrayWithObjects:@"name",@"idNum",nil];

NSArray *values=[NSArray arrayWithObjects:@"Bob",[NSNumber numberWithInt:123],nil];

NSMutableSet *dic=[NSDictionary dictionaryWithObjects:values forKeys:keys];

NSLog(@"dic count :%d",[dic count]);//得到2

NSLog(@"name is:%@",[dic objectForKey:@"name"]);//得到Bob

NSLog(@"birth is:%@",[dic objectForKey:@"birth"];//得到nil

2.遍历字典

NSArray *keys=[NSArray arrayWithObjects:@"name",@"idNum",nil];

NSArray *values=[NSArray arrayWithObjects:@"Bob",[NSNumber numberWithInt:123],nil];

NSMutableSet *dic=[NSDictionary dictionaryWithObjects:values forKeys:keys];

for(NSString *key in[dic allKeys]){

NSLog(@"%@ => %@",key,[dic objectForKey:key]);

}

3.字典字面量

NSDictionary *dic=@{

@"name":NSUserName(),

@"data":[NSDate date],

@"processInfo":[NSProcessInfo processInfo]

};

4.字典下标语法

id key=......;

id value=object[key];