NSArray *arrayM2 = @[@"1",@"2",@"3",@"4"];

//使用for循环遍历

for(int i =0;i<[arrayM2 count];i++){

NSLog(@"%@",arrayM2[i]);

}

//NSEnumerator遍历

NSEnumerator  *enumeration = [arrayM2  reverseObjectEnumerator];

NSString *object;

while  ((object = [enumeration nextObject])!=nil) {

NSLog(@"%@", object);

}

//for...In遍历

for(id  obj  in  arrayM2){

NSLog(@"%@",obj);

}

//block遍历

[arrayM2 enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {

NSLog(@"%@",obj);

}];

//GCD遍历处理耗时比较长，迭代次数较多的情况//经过测试运行遍历是无序的

dispatch_queue_t  queue = dispatch_get_global_queue(0, 0);

dispatch_apply(arrayM2.count,      queue, ^(size_t index) {

NSLog(@"%@--%@",arrayM2[index],[NSThread currentThread]);

});