iOS编程(双语版) - 视图 - Transform(转换)

视图有一个transform属性，它描述了应该如何绘制该视图。

该属性是CGAffineTransform结构体，它代表了3 x 3的变换矩阵(线性代数)。

下面的代码让两个矩形视图旋转45度

(Objective-C代码)

UIView* v1 = [[UIView alloc] initWithFrame:CGRectMake(113, 111, 132, 194)];
v1.backgroundColor = [UIColor colorWithRed:1 green:.4 blue:1 alpha:1];

UIView* v2 = [[UIView alloc] initWithFrame:CGRectInset(v1.bounds, 10, 10)];
v2.backgroundColor = [UIColor colorWithRed:.5 green:1 blue:0 alpha:1];

[mainview addSubview: v1];
[v1 addSubview: v2];
v1.transform = CGAffineTransformMakeRotation(45 * M_PI/180.0);

(Swift代码 iOS9)

let v1 = UIView(frame:CGRectMake(113, 111, 132, 194))
v1.backgroundColor = UIColor(red: 1, green: 0.4, blue: 1, alpha: 1)

let v2 = UIView(frame:v1.bounds.insetBy(dx: 10, dy: 10))
v2.backgroundColor = UIColor(red: 0.5, green: 1, blue: 0, alpha: 1)

mainview.addSubview(v1)
v1.addSubview(v2)
v1.transform = CGAffineTransformMakeRotation(45 * CGFloat(M_PI)/180.0)

记住：对父视图进行转换，子视图会跟着动。 

运行结果：

子视图先平移，再旋转

v2.transform = CGAffineTransformMakeTranslation(100, 0);
v2.transform = CGAffineTransformRotate(v2.transform, 45 * M_PI/180.0);

子视图先旋转，再平移

v2.transform = CGAffineTransformMakeRotation(45 * M_PI/180.0);
v2.transform = CGAffineTransformTranslate(v2.transform, 100, 0);
Transform

 变形变换

v1.transform = CGAffineTransformMake(1, 0, -0.2, 1, 0, 0);