How to make a button with a partially transparent background. See http://stackoverflow.com/questions/19274124/how-can-i-change-the-alpha-channel-of-a-button-in-ios-without-affecting-the-text/

SODimButton.h

#import <UIKit/UIKit.h>

@interface SODimButton : UIButton

@property (nonatomic, strong) UIColor *buttonColor;
@property (nonatomic, strong) UIColor *selectedButtonColor;

@property (nonatomic) CGFloat backgroundAlpha;

@end

SODimButton.m

#import "SODimButton.h"

@implementation SODimButton

- (void)drawRect:(CGRect)rect {
    // More drawing can be done if you get the context.
    // I actually don't use it in this example.
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    if (self.selected || self.highlighted) {
        [[self.selectedButtonColor colorWithAlphaComponent:self.backgroundAlpha] setFill];
    } else {
        [[self.buttonColor colorWithAlphaComponent:self.backgroundAlpha] setFill];
    }
    UIRectFill(rect);
}

- (void)setSelected:(BOOL)selected {
    [super setSelected:selected];
    [self setNeedsDisplay];
}

- (void)setHighlighted:(BOOL)highlighted {
    [super setHighlighted:highlighted];
    [self setNeedsDisplay];
}

@end

ViewController.m

- (void)viewDidLoad {
    [super viewDidLoad];
    
    SODimButton *button = [[SODimButton alloc] initWithFrame:CGRectMake(self.view.frame.size.width / 2 - 100, 50, 200, 44)];
    [button setTitle:@"My Button" forState:UIControlStateNormal];
    [button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    button.buttonColor = [UIColor redColor];
    button.selectedButtonColor = [UIColor colorWithRed:0.73f green:0.10f blue:0.00f alpha:1.00f];
    button.backgroundAlpha = 0.2f;
    [self.view addSubview:button];
}