精通IOS开发第六版学习第五章---旋转和布局

这一章主要介绍了两种方法设置屏幕的旋转和自动布局

1. 使用constraints

在story board 中完成

2. 使用代码的方式

主要介绍这种方式

需要去除view的auto layout.

效果如下：

代码如下：

////  ViewController.m//  L05-Restructure////  Created by zhengna on 15/6/24.//  Copyright (c) 2015年 zhengna. All rights reserved.//#import "ViewController.h"@interface ViewController ()@property (weak, nonatomic) IBOutlet UIButton *actionButton1;@property (weak, nonatomic) IBOutlet UIButton *actionButton2;@property (weak, nonatomic) IBOutlet UIButton *actionButton3;@property (weak, nonatomic) IBOutlet UIButton *actionButton4;@property (weak, nonatomic) IBOutlet UIView *contentView;@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.    UIApplication *app = [UIApplication sharedApplication];    UIInterfaceOrientation currentOrientation = app.statusBarOrientation;    [self doLayoutForOrientation:currentOrientation];}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration{    [self doLayoutForOrientation:toInterfaceOrientation];}- (void)doLayoutForOrientation:(UIInterfaceOrientation)orientation{    if (UIInterfaceOrientationIsPortrait(orientation)) {        [self layoutPortrait];    }else{        [self layoutLandscape];    }}static const CGFloat buttonHeight = 40;static const CGFloat buttonWidth = 120;static const CGFloat spacing =20;- (void)layoutPortrait{    CGRect b = self.view.bounds;        CGFloat contentWidth = CGRectGetWidth(b) - (2 * spacing);    CGFloat contentHeight = CGRectGetHeight(b) - (4 * spacing) - (2 * buttonHeight);        self.contentView.frame = CGRectMake(spacing, spacing, contentWidth, contentHeight);        CGFloat buttonRow1y = contentHeight + (2 * spacing);    CGFloat buttonRow2y = buttonRow1y + buttonHeight + spacing;        CGFloat buttonCol1x = spacing;    CGFloat buttonCol2x = CGRectGetWidth(b) - buttonWidth - spacing;        self.actionButton1.frame = CGRectMake(buttonCol1x, buttonRow1y, buttonWidth, buttonHeight);    self.actionButton2.frame = CGRectMake(buttonCol2x, buttonRow1y, buttonWidth, buttonHeight);    self.actionButton3.frame = CGRectMake(buttonCol1x, buttonRow2y, buttonWidth, buttonHeight);    self.actionButton4.frame = CGRectMake(buttonCol2x, buttonRow2y, buttonWidth, buttonHeight);    }- (void)layoutLandscape{    CGRect b = self.view.bounds;        CGFloat contentWidth = CGRectGetWidth(b) - buttonWidth - (3 * spacing);    CGFloat contentHeight = CGRectGetHeight(b) - (2 * spacing);        self.contentView.frame = CGRectMake(spacing, spacing, contentWidth, contentHeight);        CGFloat buttonX = CGRectGetWidth(b) - buttonWidth - spacing;    CGFloat buttonRow1y = spacing;    CGFloat buttonRow4y = CGRectGetHeight(b) - buttonHeight - spacing;    CGFloat buttonRow2y = buttonRow1y + floor((buttonRow4y - buttonRow1y) * 0.333);    CGFloat buttonRow3y = buttonRow1y + floor((buttonRow4y - buttonRow1y) * 0.667);        self.actionButton1.frame = CGRectMake(buttonX, buttonRow1y, buttonWidth, buttonHeight);    self.actionButton2.frame = CGRectMake(buttonX, buttonRow2y, buttonWidth, buttonHeight);    self.actionButton3.frame = CGRectMake(buttonX, buttonRow3y, buttonWidth, buttonHeight);    self.actionButton4.frame = CGRectMake(buttonX, buttonRow4y, buttonWidth, buttonHeight);    }@end

这里主要涉及几个新事物：

1. CGRect 方形

2. bounds and frame 它们都是一种CGRect

3. CGRectMake(): let you easily create a CGRect 快速生成一个Rect并把它放入父容器
4. CGRectGetHeight() 求它的高
5. CGRectGetWidth() 求它的宽

程序根据不同的屏幕方向，运用不同的计算方法计算出view中几个element的位置和大小。