在此主要介紹UIButton的一些特殊用法：UIButton的圖片與文字排版渴肉，UIButton的UIControlEvents限佩，以及UIButton背景圖片設(shè)置蔚润，至于給UIButton設(shè)置frame焚挠，UIButtonType之類的基礎(chǔ)知識蟹肘，就不做介紹璃吧。

一楣导、UIButton的圖片與文字排版

UIButton可以同時設(shè)置title和image，但如果不對title和image的位置進行調(diào)整畜挨，排版會很丑筒繁，如下：

    UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
    btn.frame = CGRectMake(90, 180, 100, 40);
    btn.layer.cornerRadius = 20;
    btn.backgroundColor = [UIColor cyanColor];
    [btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    
    [btn setTitle:@"title" forState:UIControlStateNormal];
    [btn setImage:[UIImage imageNamed:@"co_ch_t"] forState:UIControlStateNormal];
    
    [self.view addSubview:btn];

不作任何處理的效果

    UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
    btn.frame = CGRectMake(90, 180, 100, 40);
    btn.layer.cornerRadius = 20;
    btn.backgroundColor = [UIColor cyanColor];
    [btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    
    [btn setTitle:@"title" forState:UIControlStateNormal];
    [btn setImage:[UIImage imageNamed:@"co_ch_t"] forState:UIControlStateNormal];
    
    btn.titleEdgeInsets = UIEdgeInsetsMake(0.0,  0.0, 0.0,  - 10);
    btn.imageEdgeInsets = UIEdgeInsetsMake(0.0, - 10, 0.0, 0.0);
    
    [self.view addSubview:btn];

變美了~

自然，在開發(fā)的過程中修己，我們會遇到很多不一樣的需求臊旭，比如圖片在文字右邊，圖片在文字上邊箩退，等等离熏，我們都可以通過改變UIButton的titleEdgeInsets和imageEdgeInsets這兩個屬性來實現(xiàn)。
下面列舉一些排版例子：

    // 圖片在左邊戴涝，全部居中
    CGFloat spacing = 20;
    CGSize imageSize = btn0.imageView.frame.size;
    btn0.titleEdgeInsets = UIEdgeInsetsMake(0.0,  0.0, 0.0,  - spacing/2);
    // 對titleEdgeInsets的屬性賦值之后滋戳，title的寬度可能會變化钻蔑，所以我們需要在titleEdgeInsets賦值之后去獲取titleSize
    CGSize titleSize = btn0.titleLabel.frame.size;
    btn0.imageEdgeInsets = UIEdgeInsetsMake(0.0, - spacing/2, 0.0, 0.0);
    
    // 圖片在上邊，全部居中
    imageSize = btn1.imageView.frame.size;
    titleSize = btn1.titleLabel.frame.size;
    spacing = 2;
    btn1.titleEdgeInsets = UIEdgeInsetsMake(0.0, - imageSize.width, - (imageSize.height + spacing/2), 0.0);
    titleSize = btn1.titleLabel.frame.size;
    btn1.imageEdgeInsets = UIEdgeInsetsMake(- (titleSize.height + spacing/2), 0.0, 0.0, - titleSize.width);
    
    // 圖片在右邊奸鸯，全部居中
    spacing = 20;
    imageSize = btn2.imageView.frame.size;
    btn2.titleEdgeInsets = UIEdgeInsetsMake(0.0, - imageSize.width, 0.0, imageSize.width + spacing/2);
    titleSize = btn2.titleLabel.frame.size;
    btn2.imageEdgeInsets = UIEdgeInsetsMake(0.0, titleSize.width + spacing/2, 0.0, - titleSize.width);
    
    // 圖片在右邊咪笑，文字居中
    imageSize = btn3.imageView.frame.size;
    btn3.titleEdgeInsets = UIEdgeInsetsMake(0.0, - imageSize.width, 0.0, 0.0);
    titleSize = btn3.titleLabel.frame.size;
    btn3.imageEdgeInsets = UIEdgeInsetsMake(0.0, titleSize.width + imageSize.width + spacing, 0.0, - titleSize.width);

效果圖

二、UIButton的UIControlEvents

點擊UIButton娄涩，不僅僅會觸發(fā)添加在UIButton上的觸發(fā)事件窗怒，還會根據(jù)點擊動作，手指移開UIButton范圍等操作進行響應(yīng)蓄拣，就如聊天軟件中的錄音按鈕扬虚，根據(jù)手指的移動做各種需求處理，在此球恤，就會用到UIButton的UIControlEvents屬性：

typedef NS_OPTIONS(NSUInteger, UIControlEvents) {
        // 手指按下按鈕之后辜昵，在按鈕范圍內(nèi)滑動
        // 之前會先響應(yīng) UIControlEventTouchDown
        UIControlEventTouchDragInside ,
        
        // 手指按下按鈕之后，在按鈕范圍外滑動
        // 之前會依次先響應(yīng) UIControlEventTouchDown咽斧，UIControlEventTouchDragInside
        UIControlEventTouchDragOutside ,
        
        // 手指按下按鈕的時候觸發(fā)
        UIControlEventTouchDown ,
        
        // 手指按下按鈕之后堪置，在按鈕范圍內(nèi)抬起
        // 之前會依次先響應(yīng) UIControlEventTouchDown
        UIControlEventTouchUpInside ,
        
        // 手指按下按鈕之后，在按鈕范圍外抬起
        // 之前會依次先響應(yīng) UIControlEventTouchDown张惹，UIControlEventTouchDragInside舀锨，UIControlEventTouchDragOutside
        UIControlEventTouchUpOutside
    };
    
    // 給btn添加各種UIControlEvents，并添加觸發(fā)方法宛逗，在各個方法做相應(yīng)操作
    [btn addTarget:self action:@selector(record_btn_dragged:with_event:) forControlEvents:UIControlEventTouchDragInside];
    [btn addTarget:self action:@selector(record_btn_dragged2:with_event:) forControlEvents:UIControlEventTouchDragOutside];
    [btn addTarget:self action:@selector(record_btn_touched_down) forControlEvents:UIControlEventTouchDown];
    [btn addTarget:self action:@selector(record_btn_touched_up:with_event:) forControlEvents:UIControlEventTouchUpInside];
    [btn addTarget:self action:@selector(record_btn_touched_up2:with_event:) forControlEvents:UIControlEventTouchUpOutside];

三雁竞、UIButton背景圖片設(shè)置

UIButton背景圖片設(shè)置有兩種方法，在我上一篇《iOS - 背景圖片大小的調(diào)整》中有介紹拧额。