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(, , , )];
v1.backgroundColor = [UIColor colorWithRed: green:. blue: alpha:];

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

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

(Swift代码 iOS9)

let v1 = UIView(frame:CGRectMake(, , , ))
v1.backgroundColor = UIColor(red: , green: 0.4, blue: , alpha: )

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

mainview.addSubview(v1)
v1.addSubview(v2)
v1.transform = CGAffineTransformMakeRotation( * 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(, );
v2.transform = CGAffineTransformRotate(v2.transform,  * M_PI/180.0);

子视图先旋转，再平移

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

变形变换

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