UI第二节 视图交互与事件机制

UIButton事件机制
结合空模板， ViewController
button的状态和一些常用定制
buttonType 注意iOS7之后，UIButtonTypeRoundedRect 无效果
title
UIControlState
titleColor
tintColor
currentTitle
setBackgroundImage:forState:
setImage:forState:
layer.cornerRadius
layer.borderColor
layer.borderWidth

其他注意事项：
1. button add 多个target
2. 系统样式 buttonWithType:UIButtonTypexxx
3. titleLabel
4. showTouchWhenHighlighted
5. enabled 效果：点一次label计数加1，点到10不能点
6. image @2x
UIImage:
iPhone 1/3G/3GS   320*480点 <--> 320*480像素 GoogleIcon.png [100*100pixel]
iPhone 5/5c/5s 320*568点 <--> 640*1136像素
[email protected] [200*200pixel]

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
button.frame = CGRectMake(20, 20, 100, 100);
[button setImage:[UIImage imageNamed:@"GoogleIcon.png"]];

根据分辩率的不同，自动选择图片。
iPhone 1: GoogleIcon.png
iPhone 5/5s: [email protected]
7. button addTarget:self ....内存注意事项
     // add target/action for particular event. you can call this multiple times and you can specify multiple target/actions for a particular event.
     // passing in nil as the target goes up the responder chain. The action may optionally include the sender and the event in that order
     // the action cannot be NULL. Note that the target is not retained.
     - (void)addTarget:(id)target action:(SEL)action forControlEvents:(UIControlEvents)controlEvents;
8. NSTimer示例







9. 飘落的雪花


button chess






- (void)buttonClick:(UIButton *)button {
    if ([button currentTitle]) {
        _lastSelectedButton = button;
    } else if (_lastSelectedButton && [button currentTitle] == nil) {
        CGRect frame = button.frame;
        button.frame = _lastSelectedButton.frame;
        _lastSelectedButton.frame = frame;
        
        [self.view bringSubviewToFront:button];
        [self.view bringSubviewToFront:_lastSelectedButton];
        
        _lastSelectedButton = nil;
    }
}

//button，是我们当前点击的button
// 这样也可以
- (void)buttonClick:(UIButton*)button
{
    if(button.currentTitle.length > 0)
    {
        //判断当前选中的按钮上文字的长度，如果 > 0认为有文字
        //记录当前点击的button
        _currentMoveButton = button;
    }
    
    //移动的条件
    //1:当前可以移动的button不为空
    //2:要移动到一个标题为空的位置
    if (_currentMoveButton != nil && button.currentTitle.length == 0) {
        //交换二个button的位置
        CGRect rect = _currentMoveButton.frame;
        _currentMoveButton.frame = button.frame;
        button.frame = rect;
        
        //把button提到最前面，防止被盖掉
        [self.window bringSubviewToFront:_currentMoveButton];
        [self.window bringSubviewToFront:button];
    }
}

作业：计算器