引言
一个iOS程序之所以能显示到屏幕上，完全是因为它有UIWindow;也就说，没有UIWindow，就看不见任何UI界面。
I UIWindow
键盘也是UIWindow
1.1 添加View到UIWindow中的方式
两种常用方式
- (void)addSubview:(UIView *)view;//直接将UIView添加到UIWindow中，但并不会理会view对应的UIViewController
@property(nullable, nonatomic,strong) UIViewController *rootViewController NS_AVAILABLE_IOS(4_0); // default is nil；自动将rootViewController的view添加到UIWindow中，负责管理rootViewController的生命周期
1.2 常用方法
makeKeyWindow、makeKeyAndVisible
- (void)makeKeyWindow;//让当前UIWindow变成keyWindow（主窗口）Makes the receiver the main window.
- (void)makeKeyAndVisible; // convenience. most apps call this to show the main window and also make it key. otherwise use view hidden property;Makes the receiver the key window and visible.让当前UIWindow变成keyWindow，并显示出来
1.3 UIWindow的对象获取
获取UIWindow
/**方式一：@property(nonatomic,readonly) NSArray<__kindof UIWindow *> *windows; */
[UIApplication sharedApplication].windows//在本应用中打开的UIWindow列表，这样就可以接触应用中的任何一个UIView对象(平时输入文字弹出的键盘，就处在一个新的UIWindow中)
/** 方式二：@property(nullable, nonatomic,readonly) UIWindow *keyWindow;*/
[UIApplication sharedApplication].keyWindow//用来接收键盘以及非触摸类的消息事件的UIWindow，而且程序中每个时刻只能有一个UIWindow是keyWindow。如果某个UIWindow内部的文本框不能输入文字，可能是因为这个UIWindow不是keyWindow
/** 方式三：@property(nullable, nonatomic,readonly) UIWindow *window;*/
view.window//获得某个UIView所在的UIWindow
II 案例
2.1点菜系统
/
// ViewController.m
// 20160331-点菜系统
//
// Created by devzkn on 3/31/16.
// Copyright © 2016 hisun. All rights reserved.
//
#import "ViewController.h"
@interface ViewController () <UIPickerViewDataSource,UIPickerViewDelegate>
@property (weak, nonatomic) IBOutlet UILabel *mainLabel;
@property (weak, nonatomic) IBOutlet UILabel *drinkLabel;
@property (nonatomic,strong) NSArray *foodsData;
@property (weak, nonatomic) IBOutlet UILabel *fruitLabel;
@property (weak, nonatomic) IBOutlet UIPickerView *pickerView;
@end
@implementation ViewController
-(NSArray *)foodsData{
if (nil == _foodsData) {
_foodsData = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"foods" ofType:@"plist"]];
}
return _foodsData;
}
- (void)viewDidLoad {
[super viewDidLoad];
//初始化label数据
[self.fruitLabel setText:self.foodsData[0][0]];
[self.mainLabel setText:self.foodsData[1][0]];
[self.drinkLabel setText:self.foodsData[2][0]];
}
/** 产生随机的下标 */
- (IBAction)randomMenu {
/** 方式一 */
// int row0 = arc4random_uniform([self.foodsData[0] count]);
// int row1 = arc4random_uniform([self.foodsData[1] count]);
// int row2 = arc4random_uniform([self.foodsData[2] count]);
// [self pickerView:self.pickerView didSelectRow:row0 inComponent:0];
// [self pickerView:self.pickerView didSelectRow:row1 inComponent:1];
// [self pickerView:self.pickerView didSelectRow:row2 inComponent:2];
// //切换pickerView的选择的行,
// [self.pickerView selectRow:row0 inComponent:0 animated:YES];//Selects a row in a specified component of the picker view.
// [self.pickerView selectRow:row1 inComponent:1 animated:YES];//Selects a row in a specified component of the picker view.
// [self.pickerView selectRow:row2 inComponent:2 animated:YES];//Selects a row in a specified component of the picker view.
/** 方式二*/
for (int i = 0; i< self.foodsData.count; i++) {//i 代表分组下标
//获取旧的选择行
int oldRow = [self.pickerView selectedRowInComponent:i];//Returns the index of the selected row in a given component.
//计算行数
int row = oldRow;
while (oldRow == row) {
row = arc4random_uniform([self.foodsData[i] count]);
}
//更新label
[self pickerView:self.pickerView didSelectRow:row inComponent:i];
//更新选择的行
[self.pickerView selectRow:row inComponent:i animated:YES];
}
}
#pragma
// returns the number of 'columns' to display.
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
return self.foodsData.count;
}
// returns the # of rows in each component..
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{
return [self.foodsData[component] count];
}
#pragma
- (nullable NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component __TVOS_PROHIBITED{
return self.foodsData[component] [row];
}
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component __TVOS_PROHIBITED{
//避免魔法数组，可采用enum
switch (component) {
case 0:
[self.fruitLabel setText:self.foodsData[component][row]];
break;
case 1:
[self.mainLabel setText:self.foodsData[component][row]];
break;
case 2:
[self.drinkLabel setText:self.foodsData[component][row]];
break;
}
}
@end
2.2 国旗选择
#pragma
/** 通常用于自定义UIPickerTableView 的UIPickerTableViewTitleCell*/
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(nullable UIView *)view __TVOS_PROHIBITED{
HSFlagsCellView *cell = nil;
HSFlagsModel *model = self.flagsList[row];
if (view != nil) { //代表有空循环使用的view
//只须设置下数据模型
cell =(HSFlagsCellView *) view;
[cell setFlagsModel:model];//数据装配
}else{
cell = [HSFlagsCellView pickerVieCellWithFlagsModel:model pickerView:pickerView];
}
NSLog(@" %d--%p",row,cell);
return cell;
}
- (CGFloat) pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component{
return 44;
}
2.3 省市联动
/** 设置分组的表格内容 */
- (UIView *) pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view{
UILabel *label = nil;
if (view != nil) {
label = (UILabel *)view;
}else{
label = [[UILabel alloc]init];
}
NSString *text = nil;
if (component == 0) {
text = [self.provincesList[row] name] ;
[label setBackgroundColor:[UIColor lightGrayColor]];
}else{//第二组的数据
//确定目前省所在的分组选择中的行数
NSLog(@"%d %d ",self.provincesIndex,row);
text = [self.provincesList[self.provincesIndex] cities][row];
[label setBackgroundColor:[UIColor magentaColor]];
}
[label setText:text];
return label;
}
/** 设置选择的省份索引 */
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{
if (component == 0) {
self.provincesIndex = row;
[pickerView reloadComponent:1];
//设置城市分组选择第一行
[pickerView selectRow:0 inComponent:1 animated:YES];
}
}
/** 设置分组宽度*/
- (CGFloat) pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component{
if (component == 0) {
return 150;
}else{
return 100;
}
}
see also
🍅 iOS逆向（公号：iosrev）
🍅 简历模板、技术互助。关注我，都给你。
