iOS development à la carte system using Uipickerview

Use Uipickerview to implement a simple à la carte interface as shown in. Source Address: Https://github.com/xiaoLong1010/iOSAppDemo.git

Uipickerview has two protocol Uipickerviewdatasource,uipickerviewdelegate, which provide data and proxies for Uipickeview. Uipickeview's three component represent Fruit,main,drink, select a row, and the menu name is shown below. At the top of the random button, a random à la carte function is implemented.

1.viewController implements two protocols and references related data and controls.

@interface Csyviewcontroller () <UIPickerViewDataSource,UIPickerViewDelegate>** * * *  **randbtn; @end

2. The data is stored in the plist file, referenced by Foodgroup, and read with lazy loading.

// Override getter method, lazy load implementation -(Nsarray *) foodgroups{    if (!  _foodgroups) {        *path = [[NSBundle mainbundle] Pathforresource:@ "foods.plist" Oftype:nil];                 = [Nsarray arraywithcontentsoffile:path];    }         return _foodgroups;    }

Information provided by 3.UIPickerViewDataSource: Number of component and how many rows per component

#pragma Mark--Uipickerviewdatasource// return component number -(Nsinteger) Numberofcomponentsinpickerview: (Uipickerview *) pickerview{    return  Self.foodGroups.count;} // returns the number of rows per component -(Nsinteger) Pickerview: (Uipickerview *) Pickerview numberofrowsincomponent: ( Nsinteger) component{    return  [self.foodgroups[component] count];}

4.UIPickerViewDelegate provides the data displayed for each row.

#pragma Mark--uipickerviewdelegate// each row displays the data, string data -(NSString *) Pickerview: ( Uipickerview *) Pickerview Titleforrow: (nsinteger) Row forcomponent: (nsinteger) component{    return  Self.foodgroups[component][row];}

5. After you select a row in Uipickerview, you need to dynamically change the menu name below. This is done by the Didselectrow: method of the Uipickerviewdelegate protocol, which is automatically called by a row in the selected line. That is, changing the name of the dish dynamically in the method.

- (void) viewdidload{[Super Viewdidload];//For (Nsarray *group in self.foodgroups) {//Csylog (@ "%@", group);//    }        //initialize three label, menu name     for(inti =0; i < Self.foodGroups.count; i++) {[Self pickerView:self.picker didselectrow:4INCOMPONENT:I]; }    //Nsinteger row = [Self.picker selectedrowincomponent:0];//Csylog (@ "Selected row =%d", row); //Monitoring Methods[self.randbtn addtarget:self Action: @selector (Randbtndidclick:) forcontrolevents:uicontroleventtouchupinside]        ; }#pragmaMark--randbtn listener-(void) Randbtndidclick: (UIButton *) button{//Csylog (@ "click");         for(inti =0; i < Self.foodGroups.count; i++) {Nsarray*group =Self.foodgroups[i]; Nsinteger NewRow= Arc4random ()%Group.count; //rows that were previously selectedNsinteger CurrentRow =[Self.picker selectedrowincomponent:i];//NSLog (@ "CurrentRow =%d", currentrow); //if the random value is equal to the current value, the random value adds 1 .        if(NewRow = =CurrentRow) {NewRow= (NewRow +1) %Group.count; }//NSLog (@ "NewRow =%d", newRow); //Select a row of a column[Self.picker selectrow:newrow incomponent:i Animated:yes]; //Call the Didsecled method, update three labels[self pickerView:self.picker didselectrow:newrow incomponent:i]; }        }