问题
I am trying to call and alert when a button is pressed. i use this :
-(IBAction)Add {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle: @"add button pressed"
message:@"Add to record"
delegate:nil
cancelButtonTitle:@"Cancel"
otherButtonTitles:@"OK", nil ];
[alert show];
[alert release];
}
ok , no problem here, two button came up, OK and cancel. Now i want detect which button is pressed i use:
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
// the user clicked one of the OK/Cancel buttons
if (buttonIndex == 0)
{
//just to show its working, i call another alert view
UIAlertView *alert = [[UIAlertView alloc] initWithTitle: @"OK WORKIng well"
message:@"no error" delegate:nil
cancelButtonTitle:@"IWORKS"
otherButtonTitles:@"NO PRB", nil];
[alert show];
[alert release];
}
else
{
NSLog(@"cancel");
}
}
now here is the problem. i cannnot detect which button is pressed; the 2nd alertview doesnt show. i've check through the code a couple of times, there doesn't seem to be any problem with it. no error/warning too.
回答1:
To detect the button clicks the alert view must have an associated delegate, e.g.
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"add button pressed"
message:@"Add to record"
delegate:self // <------
cancelButtonTitle:@"Cancel"
otherButtonTitles:@"OK", nil];
回答2:
This is your code which i used and added some my code also. **
-(IBAction) Add
{
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"add button pressed"
message:@"Add to record"
delegate:nil
cancelButtonTitle:@"Cancel"
otherButtonTitles:@"OK", nil];
alert.tag=101;//add tag to alert
[alert show];
[alert release];
}
Now when you press button on alert it will call clickedButtonAtIndex but there should a identifier for every alert. So add tag and then
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex**
{
// the user clicked one of the OK/Cancel buttons
if(alertView.tag == 101) // check alert by tag
{
if (buttonIndex == 0)
{
//just to show its working, i call another alert view
UIAlertView *alert = [[UIAlertView alloc] initWithTitle: @"OK WORKIng well"
message:@"no error"
delegate:nil
cancelButtonTitle:@"IWORKS"
otherButtonTitles:@"NO PRB", nil];
[alert show];
[alert release];
}
else
{
NSLog(@"cancel");
}
}
}
Hope it helps.
回答3:
The buttonIndex of 0 is the cancel button. I would recommend using:
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
if (buttonIndex == 0)
{
NSLog(@"cancel");
}
else
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"OK works" message:@"no error" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
[alert release];
}
}
回答4:
I feel if you wish to show a new alert view on button click event of an existing alert view, it would be better to use
- (void) alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
}
delegate method instead of
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
}
回答5:
1)
.h file
@interface MyClassViewController:<UIAlertViewDelegate>
2)
.m file
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Note"
message:@"some message"
delegate:self // must be self to call clickedButtonAtIndex
cancelButtonTitle:@"Cancel"
otherButtonTitles:@"OK", nil];
3)
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
if (buttonIndex == [alertView cancelButtonIndex]) {
NSLog(@"The cancel button was clicked from alertView");
}
else {
}
}
回答6:
If you prefer your code to be cleaner and no dependency on delegate, you should try the blocks implementation of UIAlertView:
https://github.com/steipete/PSAlertView
Blocks are only supported on iOS 4+ devices though.
来源：https://stackoverflow.com/questions/3491724/detecting-button-click-with-uialertview