Setting a background image for UIButton

I am a newbie with Objective C. How would I set the background of this button to an image (image is already in the resources folder in XCode, "blue_button.png") instead of clearColor? Also, I would prefer that I use the image as the shape of the button rather than the UIButtonTypeRoundedRect.

btnClear = [[UIButton buttonWithType:UIButtonTypeRoundedRect] retai开发者_运维问答n];

btnClear.frame = CGRectMake(115, 350, 90, 40);

[btnClear setTitle:@"Clear" forState:UIControlStateNormal];

btnClear.backgroundColor = [UIColor clearColor];

[btnClear addTarget:self action:@selector(clearAction:) 

forControlEvents:UIControlEventTouchUpInside];

[self.view addSubview:btnClear];

I know how to do this in Interface Builder but I would rather learn about doing it in XCode.

This works:

UIButton *btnClear = [[UIButton alloc] init];
btnClear = [[UIButton buttonWithType:UIButtonTypeCustom] retain];
btnClear.frame = CGRectMake(115, 200, 90, 40);
[btnClear setTitle:@"Clear" forState:UIControlStateNormal];
[btnClear setBackgroundImage:[UIImage imageNamed:@"blue_button.png"] forState:UIControlStateNormal];
[btnClear addTarget:self action:@selector(clearAction:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:btnClear];

See the UIButton class reference: -setBackgroundImage:forState:

Create your button with type UIButtonTypeCustom instead of UIButtonTypeRoundedRect if you don't want to use the rounded corner style.

You need to declare your button with the following UIButtonTypeCustom type:

btnClear = [[UIButton buttonWithType:UIButtonTypeCustom] retain];

Then you should be able to use the follow:

[btnClear setImage:[UIImage imageNamed:@"blue_button.png"] forState:UIControlStateNormal];

There are 6 different control states that can be set.

enum {
   UIControlStateNormal               = 0,
   UIControlStateHighlighted          = 1 << 0,
   UIControlStateDisabled             = 1 << 1,
   UIControlStateSelected             = 1 << 2,
   UIControlStateApplication          = 0x00FF0000,
   UIControlStateReserved             = 0xFF000000
};

Here are some references that may help:

UIButton Class Reference

UIControl Class Reference

You can use [UIColor colorWithPatternImage:] to set background color to image. To use image you should change button style to custom.

Swift 4+

var btnClear = UIButton()
btnClear = UIButton(type: .custom)
btnClear.frame = CGRect(x: 115, y: 200, width: 90, height: 40)
btnClear.setBackgroundImage(UIImage(named: "blue_button.png"), for: .normal)
view.addSubview(btnClear)

if you want to set button background with images on the Internet, using SDWebImage is an elegant choice:

#import <SDWebImage/UIButton+WebCache.h>

UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(x, y, width, height)];
[button setBackgroundImageWithURL:imageURL forState:UIControlStateNormal];

No need to set button to UIButtonTypeCustom - (void)setBackgroundImage:(UIImage *)image forState:(UIControlState)state method also works for UIButtonTypeRoundedRect