UIsegmentedControl setTintColor strange behaviour

问题

I have a UISegmentedControl containing 3 options for selecting map type. I am setting tintcolor as black as default and I want to set green color for selected segment.

Here is declaration of segmented control

NSArray *mapType = [NSArray arrayWithObjects: @"Map", @"Hyb", @"Sat", nil];
    segmentedMapType = [[UISegmentedControl alloc] initWithItems:mapType] ;
    segmentedMapType.segmentedControlStyle =   UISegmentedControlStyleBar ;
    segmentedMapType.tintColor = [UIColor blackColor];
    segmentedMapType.frame = CGRectMake(100, 40, 120, 40);
   // segmentedMapType.momentary = YES;
    [[[segmentedMapType subviews]objectAtIndex:0] setTintColor:[UIColor colorWithRed:0 green:.6 blue:0 alpha:1]];
    [segmentedMapType setSelectedSegmentIndex:0];

[segmentedMapType addTarget:self action:@selector(selectMap:) forControlEvents:UIControlEventValueChanged];
[mapSettingsView addSubview:segmentedMapType];

And here is the selector method

-(void)selectMap:(id)sender
    {
        int index = [segmentedMapType selectedSegmentIndex];

        UIColor *newSelectedTintColor = [UIColor colorWithRed: 0 green:.6 blue:0 alpha:1.0];

        if (index==0) {
    [[[segmentedMapType subviews] objectAtIndex:2] setTintColor:newSelectedTintColor];
    [[[segmentedMapType subviews] objectAtIndex:1] setTintColor:[UIColor blackColor]];
    [[[segmentedMapType subviews] objectAtIndex:0] setTintColor:[UIColor blackColor]];
} else if (index==1){
    [[[segmentedMapType subviews] objectAtIndex:1] setTintColor:newSelectedTintColor];
    [[[segmentedMapType subviews] objectAtIndex:0] setTintColor:[UIColor blackColor]];
    [[[segmentedMapType subviews] objectAtIndex:2] setTintColor:[UIColor blackColor]];
}
else

if (index==2)
{
    [[[segmentedMapType subviews] objectAtIndex:0] setTintColor:newSelectedTintColor];
    [[[segmentedMapType subviews] objectAtIndex:1] setTintColor:[UIColor blackColor]];
    [[[segmentedMapType subviews] objectAtIndex:2] setTintColor:[UIColor blackColor]];
}


       }

This code works good on devices < iOS-5 but on >=iOS-5 problem with this is green tint color does not get applied to correct segment or sometimes to any segment. What is wrong with this code? Any help will be greatly appreciated.

回答1:

Thanks to this question.

As mentioned there selected index is not a reliable way to assign tintcolor. I had to store their id and use them to assign tintcolor. First store the IDs

for (int i=0; i<3; i++) {
        //The most important trick to work, have to retain the subviews
        segment[i] = [[[segmentedMapType subviews] objectAtIndex:i] retain];
    }

And then use it

-(void)selectMap:(id)sender
{
    int index = [segmentedMapType selectedSegmentIndex];
    UIColor *newSelectedTintColor = [UIColor colorWithRed: 0 green:.7 blue:0 alpha:1.0];
    for (int i=0; i<3; i++) {
        [segment[i] setTintColor:[UIColor blackColor]];
    }
    int select = segmentedMapType.selectedSegmentIndex;
    [segment[select] setTintColor:newSelectedTintColor];  
}

回答2:

for some reason if it's done in viewDidLoad (or anywhere before viewdDidAppear) changes to tint color of single segments (maybe even the whole segmented control, not sure) are not applied until you touch the control.