IOS-UI 屬性frame和bounds

在使用代碼編寫界面的時候會遇到一些重要屬性，其中frame和bounds這兩個屬性可能比較容易混淆

bounds：表示該圖示在本地座標系統中的位置和大小，相對於本身

frame：表示view在其父視圖座標系統中的位置和大小，相對於父視圖

下面看例子

@interface SecondViewController ()

@end

@implementation SecondViewController

- (void)viewDidLoad {
    [super viewDidLoad];
   
    
    UIView *viewA = [[UIView alloc] init];
    viewA.backgroundColor = [UIColor grayColor];
    //設置viewA的frame屬性
    viewA.frame = CGRectMake(0, 0, 300, 500);
    [self.view addSubview:viewA];
    
    
    
    UIView *viewB = [[UIView alloc] init];
    viewB.backgroundColor = UIColor.orangeColor;
    viewB.frame = CGRectMake(20, 80, 100, 100);
    [self.view addSubview:viewB];
    
    NSLog(@"frame-x:%0.2f, frame-y:%.3f", viewB.frame.origin.x, viewB.frame.origin.y);
    NSLog(@"frame-width:%f, frame-height:%.1f", viewB.frame.size.width, viewB.frame.size.height);
    NSLog(@"bounds-x:%0.2f, bounds-y:%.2f", viewB.bounds.origin.x, viewB.bounds.origin.y);
    NSLog(@"bounds-width:%0.2f, bounds-height:%.2f", viewB.bounds.size.width, viewB.bounds.size.height);
    
//    2018-06-28 14:12:22.333305+0800 UIViewDemo[79588:3484414] frame-x:20.00, frame-y:80.000
//    2018-06-28 14:12:22.333494+0800 UIViewDemo[79588:3484414] frame-width:100.000000, frame-height:100.0
//    2018-06-28 14:12:22.333595+0800 UIViewDemo[79588:3484414] bounds-x:0.00, bounds-y:0.00
//    2018-06-28 14:12:22.333730+0800 UIViewDemo[79588:3484414] bounds-width:100.00, bounds-height:100.00
//    上面結果還體現了佔位符問題，%f 默認取小數點後6位，%f.2表示取小數點後2位，%f0.2小國和%f.2同樣，%f.1 取小數點後一位


@end

frame-x:20.00, frame-y:80.000

frame-width:100.000000, frame-height:100.0

bounds-x:0.00, bounds-y:0.00

bounds-width:100.00, bounds-height:100.00