目錄
- UIPickerView的使用(兩個案例)
一、UIPickerView的使用
案例1:點菜系統
目標:
》使用UIPikcerView控件實現點菜系統
》掌握UIPikcerView的代理與數據源與代理方法的使用,與TableView類比
(1)UITableView的每一行Cell是在數據源裏,而UIPikcerView的每一行View是在代理裏
(2)UIPickerView每一行長什麼樣有兩個方法
//-(NSString *)pickerView: titleForRow: forComponent:直接返回一個字符串
//-(UIView *)pickerView: viewForRow: forComponent: reusingView:直接返回一個view
#pragma mark - UIPickerViewDelegate methods
//數據部分的展示是交給代理來做
- (nullable NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component;
》監聽每組選中的行,更改Label數據
(1)使用代理方法(數據源改變但是pickview沒有變化)
- (void)pickerView:didSelectRow:inComponent:
2)更改UIPickView選中的數據(讓pickview跟隨數據的改而改變)
[self.pickerView selectRow:randRow inComponent:i animated:YES];
》實現默認選中每一組的第一行數據
(1)在viewDidLoad方法調用【-(void)pickerView:didSelectRow:inComponent:】實現
》實現隨機選菜單
(1)實現Label數據的隨機變更
(2)實現pickerView的數據隨機變更
(3)每一組對應行的數據一定要不同上一次的行數據
/**
*獲取舊行與新行,使用while循環,
//舊行
NSInteger oldRow = [self.pickerView selectedRowInComponent:i];
//隨機新行
NSInteger newRow = arc4random_uniform((int)rows);
//新行與舊行相同,再隨機,直到不兩隻
while (newRow == oldRow) {
newRow = arc4random_uniform((int)rows);
}
*/
eg:
#pragma makr - 隨機產生結果
- (IBAction)randNumber:(id)sender {
//1.獲取列數
NSInteger colum = self.dataArray.count;
for (int i = 0; i < colum; i ++) {
//2.獲取隨機每列的隨機行數
NSArray *items = self.dataArray[i];
unsigned int rowCount = (unsigned int)items.count;
unsigned int randRow = arc4random_uniform(rowCount);//arc4random_uniform指定範圍,如果填arc4random_uniform(10),獲取的數是0-9
//每列的隨機行數不能與之前一樣
// 獲取舊的行數
NSInteger oldRow = [self.pickerView selectedRowInComponent:i];
while (oldRow == randRow) {
randRow = arc4random_uniform(rowCount);
}
// 0.0~0.9
//arc4random_uniform(10) * 0.1
// 0.00~0.99
//arc4random_uniform(100) * 0.01
//3.更改數據(數據源改變但是pickview沒有變化)
[self pickerView:nil didSelectRow:randRow inComponent:i];
//更改UIPickView選中的數據
[self.pickerView selectRow:randRow inComponent:i animated:YES];
}
}
案例2.國旗選擇
》掌握代理【-(UIView *)pickerView:viewForRow:forComponent:reusingView:】的使用
(1)在數據源裏返回一組數據,行數由國旗個數決定
(2)在代理方法中使用上面的方法,每一行返回一個View,返回的這個view爲label
(3)打印reusingView的地址和文字,”查看循環利用的view” –’備課的時候多演示幾次’
//eg: NSLog(@”==%p %@”,label,label.text);
(4)使用一個xib描述國家和國旗
(5)掌握一個設置行高的代理方法
#pragma mark - 自定義pickerView行
//循環引用在ios7以後,不帶明顯,但是確實還是會循環引用
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view{
//如果有重用的View,會傳一個view進來,重用
FlagView *flagView = (FlagView *)view;
if (!flagView) {
flagView = [FlagView flageView];
}
#warning 一般設置自定義的view大小時,不直接設置bounds/frame
//自定義控件要添加bounds
flagView.bounds = CGRectMake(0, 0, 200, 0);
//設置數據
flagView.modelData = self.array[row];
//打印view的內存地址
NSLog(@"row = %ld,address: %p, name = %@",row, flagView,((FlagModel *)self.array[row]).name );
return flagView;
}
//設置高度無效,需要用代理設置高度
- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component{
return 50;
}
//設置寬度
//- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component{
// return 200;
//}
#import "FlagModel.h"
@interface FlagView : UIView
+ (instancetype)flageView;
@property (nonatomic, strong) FlagModel *modelData;
@end
#import "FlagView.h"
@interface FlagView ()
@property (weak, nonatomic) IBOutlet UILabel *label;
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@end
@implementation FlagView
+ (instancetype)flageView{
//需要lastobject因爲,xib中可以拖動多個視圖,而且是同級的。
return [[[NSBundle mainBundle] loadNibNamed:@"FlagView" owner:nil options:nil] lastObject];
}
- (void)setModelData:(FlagModel *)modelData{
_modelData = modelData;
self.label.text = modelData.name;
self.imageView.image = [UIImage imageNamed:modelData.icon];
}
案例3.省市聯動
@property (nonatomic,assign)NSInteger indexOfProvice;//當前默認選中的省份
ViewController.m
// returns the number of 'columns' to display.
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
return 2;
}
// returns the # of rows in each component..
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{
//第一列省份
if (component == 0) {//省分
return self.provinces.count;
}
//第二列:獲取對應省份的城市個數
Province *province = self.provinces[self.indexOfProvice];
return province.cities.count;
}
#pragma mark 顯示數據
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
if(component == 0){//顯示省份的名字
//對應列行的省份
Province *province = self.provinces[row];
return province.name;
}
//獲取選中的城市,顯示城市名字
Province *selectedProvice = self.provinces[self.indexOfProvice];
return selectedProvice.cities[row];
}
//方法二
//-(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view{
//
// UILabel *label = (UILabel *)view;
// if (!label) {
// label = [[UILabel alloc] init];
// }
//
// if(component == 0){//顯示省份的名字
// //對應列行的省份
// Province *province = self.provinces[row];
// label.text = province.name;
// label.backgroundColor = [UIColor grayColor];
// }else{
//
// //獲取選中的城市,顯示城市名字
// Province *selectedProvice = self.provinces[self.indexOfProvice];
// label.text = selectedProvice.cities[row];
// label.backgroundColor = [UIColor blueColor];
// }
//
//
//
//
// return label;
//}
#pragma mark 選中行
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{
if (component == 0) {//第一列省的選中改變後,就要更新第二列數據
//更新選中省份的索引
self.indexOfProvice = row;
//刷新數據
//全部刷新
//[pickerView reloadAllComponents];
//部份刷新
[pickerView reloadComponent:1];
//不管之前第二列選中第幾行,重新刷新數據後,都顯示每二列的第一行
[pickerView selectRow:0 inComponent:1 animated:YES];
}
}
#pragma mark 設置寬度
-(CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component{
if (component == 0) {
return 80;
}
return 200;
}