前言：項目中，設(shè)置UIButton的顏色，背景來顯示不同的狀態(tài)是很常見的操作，比如：不可點(diǎn)置灰，點(diǎn)擊高亮等等。下面，記錄一下，在這方面踩的的坑。

1.UIButton可以設(shè)置4種狀態(tài)

typedef NS_OPTIONS(NSUInteger, UIControlState) {
    UIControlStateNormal       = 0,
    UIControlStateHighlighted  = 1 << 0,                  // used when UIControl isHighlighted is set
    UIControlStateDisabled     = 1 << 1,
    UIControlStateSelected     = 1 << 2,                  // flag usable by app (see below)
}

UIControlState是一個options而不是枚舉，也就是說，這些狀態(tài)可以組合，這就可能存在相互影響的問題，這就是UIControlState的大坑。

2.簡要介紹一下四種state所代表的意義：

• UIControlStateNormal

The normal, or default state of a control—that is, enabled but neither selected nor highlighted.
代表enable,unselected,unhighlight的狀態(tài)，這也是個坑，normal是一切你沒有設(shè)置的特殊狀態(tài)都顯示normal的狀態(tài)，不僅僅是這個。

• UIControlStateHighlighted

Highlighted state of a control. A control becomes highlighted when a touch event enters the control’s bounds, and it loses that highlight when there is a touch-up event or when the touch event exits the control’s bounds.
highlight只和事件有關(guān)，比如，當(dāng)進(jìn)入點(diǎn)擊范圍時會高亮，出去點(diǎn)擊范圍時高亮?xí)?，但前提下，這個UIButton可點(diǎn)擊，否則沒有意義。

• UIControlStateDisabled

Disabled state of a control. User interactions with disabled control have no effect and the control draws itself with a dimmed appearance to reflect that it is disabled.
這個當(dāng)UIButton不可點(diǎn)擊的時候觸發(fā)

• UIControlStateSelected

Selected state of a control. For many controls, this state has no effect on behavior or appearance.
UIButton默認(rèn)selected是NO

3.重點(diǎn)介紹這四種狀態(tài)的各種顯示

UIControlState是BitMask，3 個有效的 Bit 組合其實可以擁有 8 種狀態(tài)，分別是：

0 0 0 => UIControlStateNormal
0 0 1 => UIControlStateHighlighted
0 1 0 => UIControlStateDisabled
0 1 1 => UIControlStateHighlighted & UIControlStateDisabled
1 0 0 => UIControlStateSelected
1 0 1 => UIControlStateSelected & UIControlStateHighlighted
1 1 0 => UIControlStateSelected & UIControlStateDisabled
1 1 1 => UIControlStateSelected & UIControlStateDisabled & UIControlStateHighlighted

//設(shè)置UIButton的8種狀態(tài)
[btn setTitle: @"Normal" forState: UIControlStateNormal];
[btn setTitle: @"Highlighted" forState: UIControlStateHighlighted];
[btn setTitle: @"Disabled" forState: UIControlStateDisabled];
[btn setTitle: @"Highlighted & Disabled" forState: UIControlStateHighlighted | UIControlStateDisabled];
[btn setTitle: @"Selected" forState: UIControlStateSelected];
[btn setTitle: @"Selected & Highlighted" forState:UIControlStateSelected | UIControlStateHighlighted];
[btn setTitle: @"Selected & Disabled" forState:UIControlStateSelected | UIControlStateDisabled];
[btn setTitle: @"Selected & Highlighted & Disabled" forState: UIControlStateSelected | UIControlStateHighlighted | UIControlStateDisabled];

//設(shè)置不同的state，看UIButton的顯示
//normal
UIButton *button1 = [self getButton];
button1.center = CGPointMake(center.x, base);
[self.view addSubview: button1];

//highlight
UIButton *button2 = [self getButton];
button2.center = CGPointMake(center.x, base + space);
button2.highlighted = YES;
[self.view addSubview: button2];

//disable
UIButton *button3 = [self getButton];
button3.center = CGPointMake(center.x, base + space * 2);
button3.enabled = NO;
[self.view addSubview: button3];

//highlight & disable
UIButton *button4 = [self getButton];
button4.center = CGPointMake(center.x, base + space * 3);
button4.highlighted = YES;
button4.enabled = NO;
[self.view addSubview: button4];

//selected
UIButton *button5 = [self getButton];
button5.center = CGPointMake(center.x, base + space * 4);
button5.selected = YES;
[self.view addSubview: button5];

//selected & highlight
UIButton *button6 = [self getButton];
button6.center = CGPointMake(center.x, base + space * 5);
button6.selected = YES;
button6.highlighted = YES;
[self.view addSubview: button6];

//selected & disable
UIButton *button7 = [self getButton];
button7.center = CGPointMake(center.x, base + space * 6);
button7.selected = YES;
button7.enabled = NO;
[self.view addSubview: button7];

//highlight & disable & selected
UIButton *button8 = [self getButton];
button8.center = CGPointMake(center.x, base + space * 7);
button8.highlighted = YES;
button8.enabled = NO;
button8.selected = YES;
[self.view addSubview: button8];

有圖有真相：

UIControlState.png

總結(jié)：

1.使用UIControlState盡量精確，比如說：可點(diǎn)狀態(tài)下已選擇的高亮
2.注意高亮和不可以點(diǎn)擊狀態(tài)的組合

參考：

1.《UIButton 狀態(tài)的新理解》
2.apple文檔