IOS-Create UIActionSheet 'otherButtons' by passing in array

例子如下：
NSMutableArray*buttonTitles =[NSMutableArray array];
if(condition1){
    [buttonTitles addObject:@"Do action 1"];
}
if(condition2){
    [buttonTitles addObject:@"Do action 2"];
}
if(condition3){
    [buttonTitles addObject:@"Do action 3"];
}
if(condition4){
    [buttonTitles addObject:@"Do action 4"];
}
[buttonTitles addObject:@"Cancel"];
UIActionSheet*actionSheet =[[[UIActionSheet alloc] initWithTitle: nil delegate: self cancelButtonTitle: nil destructiveButtonTitle: nil otherButtonTitles: nil] autorelease];

for(NSString*title in buttonTitles){
    [actionSheet addButtonWithTitle: title];
}

[actionSheet setCancelButtonIndex:[buttonTitles count]-1];