OC_数组

1.都是对容器里的每一个元素的遍历
2.为了增加代码的阅读性,避免不必要的错误,尽量让forin的前部分的类型和数组里的元素类型相同

NSArray *arr = @[@"杨林", @"刘鑫琪", @"李牧燃", @"腾飞",];
for (NSString * str in arr) {
NSLog(@"%@", str);
}

NSArray *arr1 = @[@"杨林", @"刘鑫琪", @"李牧燃", @"腾飞",];
NSArray *arr2 = @[@"李珊珊", @"郭鸿瑞", @"何岸", @"流星雨"];
NSArray *arr = @[arr1, arr2];

//对arr进行forin遍历
for (NSArray *temp in arr) {
for (NSString *str in temp) {
NSLog(@"%@", str);
}
}

Student *stu1 = [[Student alloc] initWithName:@"李牧燃"];
Student *stu2 = [[Student alloc] initWithName:@"刘鑫琪"];
Student *stu3 = [[Student alloc] initWithName:@"刘山山"];
Student *stu4 = [[Student alloc] initWithName:@"腾飞"];
NSArray *arr1 = @[stu1, stu2, stu3];
NSArray *arr2 = @[stu4];
NSArray *arr = @[arr1 ,arr2];

//便利下数组里每一个学生的名字
for (NSArray *temp in arr) {
for (Student *stu in temp) {
NSLog(@"%@", stu.name);
}
}

NSArray *testArr = @[@"1", @"2", @"3"];
// 赋值
NSArray *arr = [[NSArray alloc]initWithArray:testArr];
// 作为一个元素
NSArray *arr1 = [[NSArray alloc] initWithObjects:testArr, nil];

// 空的可变数组
NSMutableArray *arr = [[NSMutableArray alloc] init];
NSMutableArray *arr1 = [NSMutableArray array];
// 非空可变数组
NSMutableArray *arr2 = [[NSMutableArray alloc] initWithObjects:@"李", @"珊", @"珊", @"傻", @"傻", nil];

NSMutableArray *arr3 = [NSMutableArray arrayWithObjects:@"李", @"珊", @"珊", @"傻", @"傻", nil];

NSMutableArray *arr3 = [NSMutableArray arrayWithObjects:@"李", @"珊", @"珊", @"傻", @"傻", nil];

// 增加一个字符串 其结果是添加到数组的最后一位
[arr3 addObject:@"瓜"];
for (NSString * str in arr3) {
NSLog(@"%@", str);
}

// 移除指定下标的字符串(例如:下标3)
[arr3 removeObjectAtIndex:3];
for (NSString * str in arr3) {
NSLog(@"%@", str);
}

// 移除指定的字符串 (移除所有相同的字符串)
[arr3 removeObject:@"傻"];
for (NSString *temp in arr3) {
NSLog(@"%@", temp);
}

// 指定下标插入一个字符串(例如:下标3)
[arr3 insertObject:@"大" atIndex:3];
for (NSString * str in arr3) {
NSLog(@"%@", str);
}

// 替换一个字符串
[arr3 replaceObjectAtIndex:0 withObject:@"刘"];
for (NSString * str in arr3) {
NSLog(@"%@", str);
}

// 交换两个字符串
[arr3 exchangeObjectAtIndex:0 withObjectAtIndex:3];
for (NSString * str in arr) {
NSLog(@"%@", str);
}

// 清空数组
[arr3 removeAllObjects];

Book *book1 = [Book bookWithName:@"西游记" price:30];
Book *book2 = [Book bookWithName:@"红楼梦" price:85];
Book *book3 = [Book bookWithName:@"三国演义" price:100];
Book *book4 = [Book bookWithName:@"水浒传" price:71];

// 四本书放到可变的数组里
NSMutableArray *book = [NSMutableArray arrayWithObjects:book1, book2, book3, book4, nil];

// 对数组进行添加操作
Book *book5 = [Book bookWithName:@"新华字典" price:88];
[book addObject:book5];
for (Book * temp in book) {
NSLog(@"%@", temp.name);
}
// 对数组进行删除操作
[book removeObjectAtIndex:2];
for (Book * temp in book) {
NSLog(@"%@", temp.name);
}

// 在数组里根据书名查找对应的书,并且对书的价钱进行修改
for (Book *temp in book) {
if ([temp.name isEqualToString:@"水浒传"]) {
temp.price = 98.7;
}
}
for (Book * temp in book) {
NSLog(@"%@, %g", temp.name, temp.price);
}

// 找到价钱在70 到 100 有多少本书, 然后把符合条件的书放在一个数组里
NSMutableArray *newBook = [NSMutableArray array];
NSInteger num = 0;
for (Book *temp in book) {
if (temp.price >= 70 && temp.price <= 100) {
num++;
[newBook addObject:temp];
}
}
NSLog(@"%ld", num);
for (Book *temp in newBook) {
NSLog(@"%@ %g", temp.name, temp.price);
}

// 找到价格是100的书,把书名改成论语

for (Book *temp in book) {
if (temp.price == 100) {
temp.name = @"论语";
}
}
for (Book *temp in book) {
NSLog(@"%@ %g", temp.name, temp.price);
}