移动带边界的视图到任意位置

将视图移动到某一个随机位置时，必须考虑这么几个问题：

1.视图必须完全符合其父视图容器的大小

2.你想为这个容器添加边界，保证其在任何情况下不会与父视图靠得太近

3.如果你使用现成的SDK包中的UIView类，你就需要处理随机中心而不是随机位置

提供一个例子，大家分享一下

#import <UIKit/UIKit.h>

@interface UIView (SubviewGeometry)

- (BOOL) canMoveToCenter: (CGPoint) aCenter inView: (UIView *) aView withInsets: (UIEdgeInsets) insets;

- (BOOL) canMoveToCenter: (CGPoint) aCenter inView: (UIView *) aView withInset: (float) inset;

- (BOOL) canMoveToCenter: (CGPoint) aCenter inView: (UIView *) aView;

- (CGPoint) centerInView: (UIView *) aView withHorizontalPercent: (float) h withVerticalPercent: (float) v;

- (CGPoint) centerInSuperviewWithHorizontalPercent: (float) h withVerticalPercent: (float) v;

- (CGPoint) randomCenterInView: (UIView *) aView withInsets: (UIEdgeInsets) insets;

- (CGPoint) randomCenterInView: (UIView *) aView withInset: (float) inset;

- (void) moveToRandomLocationInView: (UIView *) aView animated: (BOOL) animated;

- (void) moveToRandomLocationInSuperviewAnimated: (BOOL) animated;

@end

 

#import "UIView-SubviewGeometry.h"

// This is a private version of the function that appears in my UIView Frame category

// It's included here as a private function to avoid requiring the other file

CGRect rectWithCenter(CGRect rect, CGPoint center)

{

CGRect newrect = CGRectZero;

newrect.origin.x = center.x-CGRectGetMidX(rect);

newrect.origin.y = center.y-CGRectGetMidY(rect);

newrect.size = rect.size;

return newrect;

}

@implementation UIView (SubviewGeometry)

#pragma mark Bounded Placement

- (BOOL) canMoveToCenter: (CGPoint) aCenter inView: (UIView *) aView withInsets: (UIEdgeInsets) insets

{

CGRect container = UIEdgeInsetsInsetRect(aView.bounds, insets);

return CGRectContainsRect(container, rectWithCenter(self.frame, aCenter));

}

- (BOOL) canMoveToCenter: (CGPoint) aCenter inView: (UIView *) aView withInset: (float) inset

{

UIEdgeInsets insets = UIEdgeInsetsMake(inset, inset, inset, inset);

return [self canMoveToCenter:aCenter inView:aView withInsets:insets];

}

- (BOOL) canMoveToCenter: (CGPoint) aCenter inView: (UIView *) aView

{

return [self canMoveToCenter:aCenter inView:aView withInset:0];

}

#pragma mark Percent Displacement

// Move view into place as a percentage-based displacement

- (CGPoint) centerInView: (UIView *) aView withHorizontalPercent: (float) h withVerticalPercent: (float) v

{

// Move in by the inset amount and then by size of the subview

CGRect baseRect = aView.bounds;

CGRect subRect = CGRectInset(baseRect, self.frame.size.width / 2.0f, self.frame.size.height /2.0f);

 

// Return a point that is h% horizontal and v% vertical

float px = (float)(h * subRect.size.width);

float py = (float)(v * subRect.size.height);

return CGPointMake(px + subRect.origin.x, py + subRect.origin.y);

}

- (CGPoint) centerInSuperviewWithHorizontalPercent: (float) h withVerticalPercent: (float) v

{

return [self centerInView:self.superview withHorizontalPercent:h withVerticalPercent:v];

}

#pragma mark Random

// Make sure you've run srandom() elsewhere in the program

// Thanks to August Joki and manitoba98

- (CGPoint) randomCenterInView: (UIView *) aView withInsets: (UIEdgeInsets) insets

{

// Move in by the inset amount and then by size of the subview

CGRect innerRect = UIEdgeInsetsInsetRect([aView bounds], insets);

CGRect subRect = CGRectInset(innerRect, self.frame.size.width / 2.0f, self.frame.size.height /2.0f);

 

// Return a random point

float rx = (float)(random() % (int)floor(subRect.size.width));

float ry = (float)(random() % (int)floor(subRect.size.height));

return CGPointMake(rx + subRect.origin.x, ry + subRect.origin.y);

}

- (CGPoint) randomCenterInView: (UIView *) aView withInset: (float) inset

{

UIEdgeInsets insets = UIEdgeInsetsMake(inset, inset, inset, inset);

return [self randomCenterInView:aView withInsets:insets];

}

- (void) moveToRandomLocationInView: (UIView *) aView animated: (BOOL) animated

{

if (!animated)

{

self.center = [self randomCenterInView:aView withInset:5];

return;

}

 

// Why 0.3f seconds? Because that is the time used to display a keyboard

CGContextRef context = UIGraphicsGetCurrentContext();

[UIView beginAnimations:nil context:context];

[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];

[UIView setAnimationDuration:0.3f];

 

self.center = [self randomCenterInView:aView withInset:5];

 

[UIView commitAnimations];

}

- (void) moveToRandomLocationInSuperviewAnimated: (BOOL) animated

{

[self moveToRandomLocationInView:self.superview animated:animated];

}

@end