數組

一、數組
1、C語言數組與OC數組區別
C語言數組：具有相同類型的元素的有序集合
int a[10]
int *b[2]
OC中：任意類型對象的指針的集合
數組中的元素都是指針變量，這些指針變量指向某個對象

2、不可變數組NSArray：

(1)創建數組
//創建數組,以nil結尾，數組僅包括nil之前的元素
??????? //讀到nil,編譯器就認為數組結束
??????? NSArray *arr = [[NSArray alloc] initWithObjects:@"hello",@"world", nil];
??????? NSLog(@"%@", arr);
???????
??????? //通過一個數組創建一個新的數組
??????? NSArray *arr1 = [[NSArray alloc] initWithArray:arr];
??????? NSLog(@"%@", arr1);

??????? //通過類方法創建數組
??????? NSArray *arr2 = [NSArray arrayWithObjects:@"guanxi", @"baizhi", @"ajiao", nil];
??????? NSLog(@"%@", arr2);
???????
??????? NSArray *arr3 = [NSArray arrayWithArray:arr2];
??????? NSLog(@"%@", arr3);

(2)數組元素個數
NSUInteger count = [arr3 count];

(3)通過指定索引獲取元素
NSString *str = [arr3 objectAtIndex:0];

(4)獲取指定對象的索引
NSUInteger index = [arr3 indexOfObject:@"ajiao"];

(5)判斷是否包含指定對象
BOOL ret = [arr3 containsObject:@"tingfeng"];

(6)遍歷數組元素
for (int i = 0; i < [arr3 count]; i++) {
??????????? NSLog(@"%@", [arr3 objectAtIndex:i]);
??????? }
??????? //快速枚舉
??????? for (NSString *str in arr3) {
??????????? NSLog(@"%@", str);
??????? }
}

[arr3 fitstObject];數組第一位
[arr3 lastObject];數組最后一位


3、數組中存放不同類型對象指針
(1)description
//如果實現了description方法，當通過％@打印對象內容的時候，就會輸出相關數據
//如果沒有該方法，就會打印對象地址

(2)isKindOfClass
isKindOfClass判斷指針指向的對象是否是某個類的實例，或者是否是某個類的子類的實例
if ([obj isKindOfClass:[Dog class]]) {
??????????????? [obj bark];
??????????? }else{
??????????????? NSLog(@"%@", obj);
??????????? }

//Class類型 存放類的信息
??????????? //[類名/對象的指針? class]
??????????? /*
??????????? //通過字符串獲取Class
??????????? Class cls = NSClassFromString(@"Dog");
??????????? //通過Class類型的變量可以創建對象
??????????? Dog *dog = [[cls alloc] init];
??????????? [dog bark];
??????????? //通過Class類型變量獲取類名
??????????? NSString *str = NSStringFromClass([wangcai class]);
??????????? NSLog(@"%@", str);

4、字符串分割
//使用指定的字符串分割另一個字符串
??????? NSArray *arr = [str componentsSeparatedByString:@" "];

//NSCharacterSet 按照字符集中字符分割字符串
NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:@" ,"];
??????? NSArray *arr1 = [str1 componentsSeparatedByCharactersInSet:set];

?//找到分割條件
??? for (NSInteger i = 0; i < fileContent.length; i++) {
??????? unichar c = [fileContent characterAtIndex:i];
? //判斷是否是字母
??????? if (!isalpha(c)) {
??????????? str = [str stringByAppendingFormat:@"%C",c];
??????? }
??? }
??? NSArray *arr = [fileContent componentsSeparatedByCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:str]];//按照字符集合分割


5、字符串拼接
//按照指定字符串拼接字符串數組中元素
??????? NSString *str = [arr componentsJoinedByString:@"###"];

6、可變數組 NSMutableArray
??????? NSMutableArray *mArr = [[NSMutableArray alloc] initWithObjects:@"123", @"tom", nil];
??????? //在數組最后添加元素
??????? [mArr addObject:@"jerry"];
???????
??????? //在指定索引處插入元素
??????? [mArr insertObject:@"hello" atIndex:1];
???????
??????? //刪除指定元素
??????? [mArr removeObject:@"hello"];

??????? //刪除指定索引處的元素
??????? [mArr removeObjectAtIndex:1];

??????? //刪除所有元素
//??????? [mArr removeAllObjects];
//??????? NSLog(@"%@", mArr);
???????
??????? //替換指定索引處的元素
??????? [mArr replaceObjectAtIndex:1 withObject:@"world"];

??????? //交換指定索引處的元素
??????? [mArr exchangeObjectAtIndex:0 withObjectAtIndex:1];

??? ??? //可變轉化為不可變
??? ??? [arr copy];

二、數組
1、不可變數組
#創建數組#
//創建方式1
NSArray *array1 = [[NSArray alloc] initWithObjects:@"xixi",@"haha",@"hehe", nil];
//創建方式2
NSArray *array2 = [[NSArray alloc] initWithArray:array1];
//創建方式3
NSArray *array3 = @[@"xixi",@"haha",@"hehe"];
//創建方式4
NSArray *array4 = [NSArray arrayWithObjects:@"how",@"are",@"you", nil];
//創建方式5
NSArray *array5 = [NSArray arrayWithArray:array4];

#查找元素位置#
NSArray *array6 = @[@"how", @"are", @"you"];
NSUInteger index = [array6 indexOfObject:@"are"];
//結果：index = 1

#字符串分割到數組里#
NSString *str = @"You@are@the@best";
NSArray *array7 = [str componentsSeparatedByString:@"@"];
//結果：array7 = @[@"You",@"are",@"the",@"best"];

#數組連接成字符串#
NSArray *array8 = @[@"I", @"love", @"you"];
NSString *str = [array8 componentsJoinedByString:@"+"];
//結果：str = @"I+love+you"
2、可變數組
#創建數組#
//創建方式1
NSMutableArray * mArray1 = [[NSMutableArray alloc] initWithObjects:@"xixi",@"haha",@"hehe", nil];
//創建方式2
NSMutableArray * mArray2 = [[NSMutableArray alloc] initWithArray:mar1];
//創建方式3
NSMutableArray * mArray3 = [NSMutableArray arrayWithObjects:@"how",@"are",@"you", nil];
//創建方式4
NSMutableArray * mArray4 = [NSMutableArray arrayWithArray:mar3];

#增刪替換#
NSArray * array = @[@"how",@"do",@"you"];
NSMutableArray * mArray5 = [[NSMutableArray alloc] initWithArray:array];

//添加
[mArray5 addObject:@"do"];
//結果：mArray5 = @[@"how", @"do", @"you", @"do"]

//插入
[mArray5 insertObject:@"GG" atIndex:0];
//結果：mArray5 = @[@"GG", @"how", @"do", @"you", @"do"]

//刪除
[mArray5 removeObjectAtIndex:0];
//結果：mArray5 = @[@"how", @"do", @"you", @"do"]

[mArray5 removeLastObject];
//結果：mArray5 = @[@"how", @"do", @"you"]

//替換
[mArray5 replaceObjectAtIndex:0 withObject:@"what"];
//結果：mArray5 = @[@"what", @"do", @"you"]

//交換位置
[mArray5 exchangeObjectAtIndex:0 withObjectAtIndex:1]
//結果：mArray5 = @[@"do", @"what", @"you"]