objective-C 调用类方法出错 输出(lldb)

代码如下:
//类BNRItem 实现 randomItem 类方法
@implementation BNRItem

+(instancetype) randomItem
{
NSArray *randomAdjectiveList = @[@"fluffy",@"rusty",@"shiny"];
NSArray *randomNounList =@[@"bear",@"spork",@"mac"];

NSInteger adjectiveIndex = arc4random() % [randomAdjectiveList count];
NSInteger nounIndex = arc4random() % [randomNounList count];

NSString *randomName = [NSString stringWithFormat:@"%@ %@",
                        [randomAdjectiveList objectAtIndex:adjectiveIndex],
                        [randomNounList objectAtIndex:nounIndex]];

int randomValue = arc4random() % 100;

NSString *randomSerialNumber = [NSString stringWithFormat:@"%c%c%c%c%c",
                                '0' + arc4random() % 10,
                                'A' + arc4random() % 26,
                                '0' + arc4random() % 10,
                                'A' + arc4random() % 26,
                                '0' + arc4random() % 10];
BNRItem *newItem = [[self alloc] initWithItemName:randomName valueInDollars:randomValue serialNumber:randomSerialNumber];

return newItem;

}
@end

//main 调用类方法

int main(int argc, const char * argv[]) {
@autoreleasepool {
// insert code here...
BNRItem *item = [BNRItem randomItem];
NSLog(@"%@",item);
}
return 0;
}

控制台输出 (l l db)

请问怎么回事? 初学ios 按照书本输入的代码 居然出错; 调用类方法都会出此错。

程序应为数组越界或者空指针之类的原因崩溃了,给代码添加断点,看下蹦在了哪一行先

main函数里原本的方法被你删了?