小编use*_*901的帖子

我正在尝试创建一个随机显示按钮上的字母的程序.我希望能够单击按钮(开始),程序将生成一个随机字母作为按钮的标题(letter1).

每次运行此程序时,它立即崩溃:

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

-(IBAction)start:(id)sender{

int randomNumber = rand() % 25;

switch (randomNumber){
    case 0:
        [letter1 setTitle:@"A" forState:UIControlStateNormal];
        break;
    case 1:
        [letter1 setTitle:@"B" forState:UIControlStateNormal];
        break;
    case 2:
        [letter1 setTitle:@"C" forState:UIControlStateNormal];
        break;
    case 3:
        [letter1 setTitle:@"D" forState:UIControlStateNormal];
        break;
    case 4:
        [letter1 setTitle:@"E" forState:UIControlStateNormal];
        break;
    case 5:
        [letter1 setTitle:@"F" forState:UIControlStateNormal];
        break;
    case 6:
        [letter1 setTitle:@"G" forState:UIControlStateNormal];
        break;
    case 7:
        [letter1 setTitle:@"H" forState:UIControlStateNormal];
        break;
    case 8:
        [letter1 setTitle:@"I" forState:UIControlStateNormal];
        break;
    case 9:
        [letter1 setTitle:@"J" forState:UIControlStateNormal];
        break;
    case …