How can I set a button background color on iPhone?

Question

I read your question to require (as I do) a programmatic way to set button color. It's a glaring omission from the UIKit, and I couldn't get the undocumented UIGlassButton to work.

I've solved this with a single segment UISegmentedControl, which allows you to set the tintColor:

UISegmentedControl * btn = [[UISegmentedControl alloc] initWithItems:[NSArray arrayWithObject:name]];
btn.momentary = YES;
btn.segmentedControlStyle = UISegmentedControlStyleBar;
btn.tintColor = color;
[btn addTarget:self action:@selector(action:) forControlEvents:UIControlEventValueChanged];

Note please that the momentary and segmentedControlStyle properties do matter, and that an image can be used instead of a NSString * name.

A stretchable image with end caps works fine if you can use a finite set of canned images, but that doesn't fit the requirement! E.g.,

buttonImage   = [[UIImage imageNamed:@"button.png"] stretchableImageWithLeftCapWidth:26 topCapHeight:16];

I found that I needed to use a stretchable image to accomplish this. Apple's UICatalog example has one or more colored buttons that are drawn in this fashion. You could use their template image and recolor it to suit your button needs.

I'm not sure about doing this in Interface Builder, but I was able to create a button and use an image for its contents using the following code:

downloadButton = [[UIButton alloc] initWithFrame:CGRectMake(36, 212, 247, 37)];

downloadButton.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
downloadButton.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;

[downloadButton setTitle:NSLocalizedStringFromTable(@"Download", @"Localized", nil) forState:UIControlStateNormal]; 
[downloadButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
[downloadButton setFont:[UIFont boldSystemFontOfSize:14.0]];

UIImage *newImage = [[UIImage imageNamed:@"greenButton.png"] stretchableImageWithLeftCapWidth:12.0f topCapHeight:0.0f];
[downloadButton setBackgroundImage:newImage forState:UIControlStateNormal];

[downloadButton addTarget:self action:@selector(downloadNewItem) forControlEvents:UIControlEventTouchDown];

downloadButton.backgroundColor = [UIColor clearColor];
[downloadDisplayView addSubview:downloadButton];

Setting the background color of the view for a rounded-rect button will not change the background color of the button. Try making the button a custom button (the first drop-down in the inspector) and then setting the background color. You will get the desired effect :)

It seems, that button color still is an issue. The following category sets a button's backgroundimage completely programmatically via an instance method that takes a UIColor parameter. There is no need to create button backgroundimage files. It preserves button behavior based on UIControlState. And it keeps the rounded corners.

The header file UIButton+ColoredBackground.h

#import <UIKit/UIKit.h>

@interface UIButton (ColoredBackground)

- (void)setBackgroundImageByColor:(UIColor *)backgroundColor forState:(UIControlState)state;

@end

and the content of UIButton+ColoredBackground.m

#import "UIButton+ColoredBackground.h"
#import <QuartzCore/QuartzCore.h>

@implementation UIButton (ColoredBackground)

- (void)setBackgroundImageByColor:(UIColor *)backgroundColor forState:(UIControlState)state{

    // tcv - temporary colored view
    UIView *tcv = [[UIView alloc] initWithFrame:self.frame];
    [tcv setBackgroundColor:backgroundColor];

    // set up a graphics context of button's size
    CGSize gcSize = tcv.frame.size;
    UIGraphicsBeginImageContext(gcSize);
    // add tcv's layer to context
    [tcv.layer renderInContext:UIGraphicsGetCurrentContext()];
    // create background image now
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    // set image as button's background image for the given state
    [self setBackgroundImage:image forState:state];
    UIGraphicsEndImageContext();

    // ensure rounded button
    self.clipsToBounds = YES;
    self.layer.cornerRadius = 8.0;

    [tcv release];

}

@end

The new method is justed called on every UIButton instance like:

[myButton setBackgroundImageByColor:[UIColor greenColor] forState:UIControlStateNormal];