Cat learning iOS (20) UI Uipickerview_ ordering system

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Look First # #

Uipickerview Control Uipickerview Use:

Used to show many rows (row) of many columns (component) of data, more for e-commerce à la carte, City selection and so on.

Uipickerview usage:

He used to be similar to TableView, usage:

1: Set up proxies and data sources

@interface NYViewController ()<UIPickerViewDataSource, UIPickerViewDelegate>

Data Source: Uipickerviewdatasource,

1, returns how many columns
2, returns how many rows

#pragma mark-uipickerviewdatasource//Return Pickerview How many columns are there altogether?- (Nsinteger) Numberofcomponentsinpickerview: (Uipickerview *) pickerview{//return 3;    return  Self. Foods. Count;}//Returns the number of rows in column component of Pickerview- (Nsinteger) Pickerview: (Uipickerview *) Pickerview numberofrowsincomponent: (Nsinteger) component{//return 4;    //1. Get an array of corresponding columns    Nsarray*subfoods = Self. Foods[Component];//2. Returns the number of rows for the corresponding column    returnSubfoods. Count;}

Agent Uipickerviewdelegate

Returns what is shown on row row of column component

#pragma mark - UIPickerViewDelegate// 返回第component列的第row行显示什么内容- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{    // 1.获取对应列的数组    NSArrayself.foods[component];    // 2.获取对应行的标题    NSString *name = subFoods[row];    return name;}

How to monitor which line is selected

Didselectrow
When we select a row in a column, we set the corresponding data.

//When a line of Pickerview is selected, call//The selected column number and line number are passed as parameters//will only be called when a row is selected by Finger- (void) Pickerview: (Uipickerview *) Pickerview Didselectrow: (Nsinteger) Row incomponent: (Nsinteger) component{//NSLog (@ "component =%d, row =%d", component, row);    //1. Get the data for the corresponding column row    NSString*name = Self. Foods[Component] [Row];//NSLog (@ "name =%@", name);    //2. Determine which column is selected, and set the corresponding data according to the column number    if(0= = component) {//Fruit         Self. Fruitlabel. Text= name; }Else if(1= = component) {//Main course         Self. Staplelabel. Text= name; }Else{//Beverages         Self. Drinklabel. Text= name; }}

Implementing Random Events

How to get Pickerview to scroll to its own line
SelectRow Incomponent let Pickerview actively scroll to a row of a column

- (ibaction) Randomfood: (UIButton*) Sender {//Let Pickerview actively select a row    //Let Pickerview select Row row for incomponent column//[Self.pickerview selectrow:1 incomponent:0 Animated:yes];    /* [Self.pickerview selectrow:arc4random ()% incomponent:0 Animated:yes];     [Self.pickerview selectrow:arc4random ()% incomponent:1 Animated:yes];     [Self.pickerview selectrow:arc4random ()% incomponent:2 Animated:yes]; *///[Self.foods objectatindex:0]; = = Self.foods[0];//[self.foods[0] count];    /*//Generate random values based on the number of elements in each column [Self.pickerview selectrow:arc4random ()% [self.foods[0] count] incomponent:0 Animated:ye    S];    [Self.pickerview selectrow:arc4random ()% [self.foods[1] count] incomponent:1 Animated:yes];    [Self.pickerview selectrow:arc4random ()% [self.foods[2] count] incomponent:2 Animated:yes]; */     for(intComponent =0; Component < Self. Foods. Count; component++) {//Get the total number of data for the corresponding column        intTotal = [ Self. Foods[Component] count];generate random numbers based on the total number of each column (the currently generated random number)        intRandomnumber = arc4random ()% Total;//Gets the currently selected row (the row that was last randomly moved to)        intOldrow = [ Self. PickerviewSelectedrowincomponent:0];//NSLog (@ "Oldrow =%d", oldrow);        //compares the last line number with the currently generated random number if the same rebuild         while(Oldrow = = Randomnumber)        {randomnumber = Arc4random ()% Total; }//Let Pickerview scroll to a line[ Self. PickerviewSelectrow:randomnumber incomponent:component Animated:YES];//Select a row by code[ SelfPickerview:NilDidselectrow:randomnumber Incomponent:component]; }}

PS: New iOS Exchange Learning Group: 304570962 can add cat qq:1764541256 or Znycat Let's study hard together.
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Cat learning iOS (20) UI Uipickerview_ ordering system