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希望有人能幫助我,爲什麼我應該添加一個:調用該方法。爲什麼發送addTarget方法有:工作
這裏是viewDidLoad方法
- (void)viewDidLoad
{
[super viewDidLoad];
self.view.backgroundColor= [UIColor yellowColor];
//Add Button
CGRect buttonRect= CGRectMake(100, 100, 100, 44);
UIButton *clickButton=[UIButton buttonWithType:UIButtonTypeRoundedRect];
[clickButton setFrame: buttonRect];
[clickButton setTitle:@"Click Me" forState: UIControlStateNormal];
[clickButton addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:clickButton];
[self buttonPressed:clickButton];
//Add UILabel
CGRect labelViewRect= CGRectMake(50, 30, 200, 44);
UILabel *labelview= [[UILabel alloc]initWithFrame:labelViewRect];
[labelview setText:@"Hello welcome to my app!"];
//Clear the UIView button's background
[labelview setBackgroundColor:[UIColor clearColor]];
[self.view addSubview:labelview];
}
這裏是按鈕按下方法
-(void)buttonPressed:(UIButton *)sender{
NSLog(@"This button was pressed");
self.view.alpha=((double)arc4random()/0x100000000);
}
當我刪除了:從
[clickButton addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];
即我改變這上面一行的東西像這樣
[clickButton addTarget:self action:@selector(buttonPressed) forControlEvents:UIControlEventTouchUpInside];
,則拋出異常:
2012年12月29日17:56:18.209 AlphaSchoolColor [11414:C07] - [com_skminfotekViewController buttonPressed]:無法識別的選擇發送到實例0xde2f050 2012年12月29日17:56:18.210 AlphaSchoolColor [11414:C07] *終止應用程序由於未捕獲的異常 'NSInvalidArgumentException',原因: ' - [com_skminfotekViewController buttonPressed]:無法識別的選擇發送到實例0xde2f050'
問題communi ty就是這樣發生的事情:我可以從哪裏得知更多信息,瞭解它的重要性。
謝謝。