NSArry 常用方法...enumerateObjectsUsingBlock:

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{
@autoreleasepool {

NSArray * arr1 = [NSArray array];

NSArray * arr2 = [NSArray arrayWithObject:@"aaa"];

// nil 表示数组赋值结束..
NSArray * arr3 = [NSArray arrayWithObjects:@"aaa", @"bbb", nil];

NSArray * arr4 = [[NSArray alloc] initWithObjects:@"one", @"two", [NSNull null], @"four", nil];

NSArray * arr5 = [NSArray arrayWithArray:arr4];

NSLog(@"%@", arr5);

// c语言数组 大小获取 sizeof(a)/sizeof(int)

NSUInteger length = [arr5 count];
NSLog(@"%lu", length);

id variable = [arr5 objectAtIndex:3];
NSLog(@"%@", variable);

NSInteger index = [arr5 indexOfObject:@"four"];
NSLog(@"%lu", index);

BOOL b = [arr5 containsObject:@"four"];
if (b) {
NSLog(@"array contains four");
NSLog(@"four inside the array");
}
else {
NSLog(@"Array does not contain four");
NSLog(@"four not in the array");
}

// 简化版 定义数组...
NSArray * arr = @[ @"one", @"two", @"three", @"four" ];
NSLog(@"%@", arr);

// 简化版 访问 数组元素
NSString * str = arr[2];
NSLog(@"%@", str);

// 遍历数组
// 方法1:
for (int i = 0; i < arr.count; i++) {
NSLog(@"%@", arr[i]);
}
// 方法2: 快速枚举法
for (NSString * str in arr) {
NSLog(@"%@", str);
}

// 方法3: 使用block的方式, 进行访问
[arr enumerateObjectsUsingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
if (idx == 2) {
// 指针变量赋值, stop是个指针, 想修改 stop指向的内存空间的内容, *stop 赋值
*stop = YES;
}
else {

NSLog(@"%@ index = %lu", obj, idx);
}
}];
}
return 0;
}