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第一步：新建一個單視圖（single view）的工程，

命名為pickerTest，不要勾選下面兩個選項，第一個是新版本里面的，第二個是單元測試，現在用不著。

點擊next ?->creat之后，打開工具欄：

在下面的控件工具欄中往視圖上拖放一個Picker View控件，一個UIButton控件，一個UILable控件，（所有在前端可以看得見的控件都繼承自UIView）

修改UIButton的title屬性，設置為click 然后點擊分欄按鈕，為控件連線（這種方式相對于手動去寫，要快速很多）。

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依次為UILable 和 Picker View 控件添加插座變量，并且為UIButton添加Action

右擊picker控件，將 Datesource和delegate連線至File's Owner, 設置它的數據源和代理。

在 cidpViewController.h文件中添加幾個變量和遵循 UIPickerViewDelegate 協議，這樣就可以用UIPickerViewDelegate里面的幾個方法了 。

@interface cidpViewController : UIViewController<UIPickerViewDelegate>

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#import <UIKit/UIKit.h>@interface cidpViewController : UIViewController<UIPickerViewDelegate> {UILabel *lblTitle;UIPickerView *picker;NSString* strProvince;NSString* strCity;NSMutableArray* aProvince;NSMutableArray* aCity;NSArray* tempArray; } @property (strong, nonatomic) IBOutlet UIPickerView *picker;@property (strong, nonatomic) IBOutlet UILabel *lblTitle; - (IBAction)btnClick:(id)sender;@end

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#import "cidpViewController.h"@implementation cidpViewController@synthesize picker; @synthesize lblTitle;- (void)didReceiveMemoryWarning {[super didReceiveMemoryWarning];// Release any cached data, images, etc that aren't in use. }#pragma mark - View lifecycle- (void)viewDidLoad {[super viewDidLoad];//初始哈5個省份aProvince = [[NSMutableArray alloc] initWithObjects:@"北京",@"甘肅",@"山西",@"湖北",@"廣州", nil];//初始化5個數組 ，分別初始化為5個省的城市NSArray* array1 = [NSArray arrayWithObjects:@"海淀",@"昌平",@"朝陽",@"西城",@"豐臺", nil];NSArray* array2 = [NSArray arrayWithObjects:@"蘭州",@"白銀",@"張掖",@"隴西",@"天水", nil];NSArray* array3 = [NSArray arrayWithObjects:@"太原",@"大同",@"運城",@"晉城",@"五臺山", nil];NSArray* array4 = [NSArray arrayWithObjects:@"武漢",@"荊州",@"襄陽",@"贛州", nil];NSArray* array5 = [NSArray arrayWithObjects:@"廣州",@"佛山",@"尖沙咀",@"中山", nil];aCity = [[NSMutableArray alloc] initWithObjects:array1,array2,array3,array4,array5, nil];//tempArray 用來初始化第二個 ，并且引用一次，避免提前釋放，內存出錯tempArray = [array1 retain];// 用來第一次顯示UIlable，負責的話就會顯示 null，null strProvince = [aProvince objectAtIndex:0];strCity = [tempArray objectAtIndex:0];[aProvince release];[aCity release];} -(NSInteger)numberOfComponentsInPickerView:(UIPickerView*)pickerView{//返回2 表示將有兩個component（滾輪）return 2; }-(NSInteger)pickerView:(UIPickerView*)pivkerView numberOfRowsInComponent:(NSInteger)component{if(component == 0){// 返回省份數組的長度return [aProvince count];}else{//返回省份對應城市數組的長度。 [tempArray count]; }- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{if(component == 0){//返回對應row 的數組元素。return [aProvince objectAtIndex:row];}else{return [tempArray objectAtIndex:row];} }- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{if(component == 0){//返回省份對應的城市數組，tempArray = [aCity objectAtIndex:row][picker selectRow:0 inComponent:1 animated:YES];[picker reloadComponent:1];strProvience = [aProvince objectAtIndex:row];strCity = [tempArray objectAtIndex:0];}else{//城市滾輪滾動時，strCity也隨著改變。strCity = [tempArray objectAtIndex:0];}lblTitle.text = [[NSString alloc] initWithFormat:@"%@,%@",strProvince,strCity,nil]; }- (void)viewDidUnload {[self setLblTitle:nil];[self setPicker:nil];[super viewDidUnload]; }- (void)viewWillAppear:(BOOL)animated {[super viewWillAppear:animated]; }- (void)viewDidAppear:(BOOL)animated {[super viewDidAppear:animated]; }- (void)viewWillDisappear:(BOOL)animated {[super viewWillDisappear:animated]; }- (void)viewDidDisappear:(BOOL)animated {[super viewDidDisappear:animated]; }- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {// Return YES for supported orientationsreturn (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown); }- (IBAction)btnClick:(id)sender {lblTitle.text = [[NSString alloc] initWithFormat:@"%@,%@",strProvince,strCity,nil]; } -(void)dealloc{[aProvince release];[aCity release];[lblTitle release];[strCity release];[strProvince release];[picker release];[super dealloc];} @end

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@protocol UIPickerViewDataSource<NSObject> @required// returns the number of 'columns' to display. - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView;// returns the # of rows in each component.. - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component; @end

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UIPickerViewDelegate協議中的五個方法，非必須實現，

@protocol UIPickerViewDelegate<NSObject> @optional// returns width of column and height of row for each component. - (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component; - (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component;// these methods return either a plain UIString, or a view (e.g UILabel) to display the row for the component. // for the view versions, we cache any hidden and thus unused views and pass them back for reuse. // If you return back a different object, the old one will be released. the view will be centered in the row rect - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component; - (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view;- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component;@end

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轉載于:https://www.cnblogs.com/wsq724439564/p/3298979.html

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