我有这个错误:如果我同时点击UIAlertView
上的两个按钮,UIAlertView
代理将不会被调用,整个屏幕将冻结(即使警报视图被取消,也无法点击任何内容)。
以前有人见过这个bug吗?有没有办法限制UIAlertView
只能点击一个按钮?
- (IBAction)logoutAction:(id)sender {
self.logoutAlertView = [[UIAlertView alloc] initWithTitle:@"Logout"
message:@"Are you sure you want to logout?"
delegate:self
cancelButtonTitle:@"No"
otherButtonTitles:@"Yes", nil];
[self.logoutAlertView show];
}
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
if ([alertView isEqual:self.logoutAlertView]) {
if (buttonIndex == 0) {
NSLog(@"cancelled logout");
} else {
NSLog(@"user will logout");
[self performLogout];
}
self.logoutAlertView.delegate = nil;
}
}
是的,可以点击UIAlertView上的多个按钮,每次点击都会调用委托方法。但是,这不应该"冻结"你的应用程序。通过代码查找问题。
为了防止处理多个事件,请在处理第一个事件后将UIAlertView的委托属性设置为nil:
- (void)showAlert {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Title" message:@"Message" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"OK", nil];
[alert show];
}
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
// Avoid further delegate calls
alertView.delegate = nil;
// Do something
if (buttonIndex == alertView.cancelButtonIndex) {
// User cancelled, do something
} else {
// User tapped OK, do something
}
}
在iOS 8:上使用UIAlertController
if ([UIAlertController class])
{
UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Logout" message:@"Are you sure you want to logout?" preferredStyle:UIAlertControllerStyleAlert];
[alert addAction:[UIAlertAction actionWithTitle:@"No" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action)
{
NSLog(@"cancelled logout");
}]];
[alert addAction:[UIAlertAction actionWithTitle:@"Yes" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action)
{
NSLog(@"user will logout");
[self performLogout];
}]];
[self presentViewController:alert animated:YES completion:nil];
}
else
{
self.logoutAlertView = [[UIAlertView alloc] initWithTitle:@"Logout"
message:@"Are you sure you want to logout?"
delegate:self
cancelButtonTitle:@"No"
otherButtonTitles:@"Yes", nil];
[self.logoutAlertView show];
}