M beef C Original Blog--mvc value, reverse pass value

Transfer value between multiple VCs

1) Forward Pass value

When AVC launches BVC, a gives a value of B is called forward value

2) Forward Pass value implementation steps

STEP1:BVC to provide a public property

// exposes a property for receiving strings that are otherwise out of class

@property (nonatomic, copy) NSString *message;

STEP2:AVC assign values to properties exposed by BVC before the BCC is rolled out

//1. Create the BVC instances of

bviewcontroller *BVC = [[bviewcontrolleralloc] Initwithnibname:@ "Bviewcontroller"bundle:Nil ];

//2. to be BVC property assignments that are exposed

BVC. message = Self . TextField . text ;

//3. Launch

[selfpresentviewcontroller: BVC animated: YEScompletion:nil];

STEP3:BVC at a suitable time to show the value of AVC coming

-(void) viewwillappear: ( BOOL ) animated{

[superviewwillappear: animated];

self. label . text = Self . message ;

}

3) Reverse transmit value (callback)

AVC introduced BVC, in the process of B return to A, b to a pass value is called the reverse value

Solution One:

Step1: Adds a property for AVC to receive the returned data

// exposes a property that is used to receive B return value of the callback

@property (nonatomic, copy) NSString *backmessage;

Step2: Adds a property for BVC to receive AVC references

// exposes an attribute that is used to store AVC the reference

@property (nonatomic,strong) Aviewcontroller *AVC;

STEP3:AVC assigns itself to BVC-exposed properties before launching BVC

#import "AViewController.h"

#import "BViewController.h"

@interfaceaviewcontroller ()

@property (weak,nonatomic) Iboutlet UILabel *label;

@end

@implementation Aviewcontroller

-(void) viewdidload

{

[superviewdidload];

}

-(void) viewwillappear: ( BOOL ) animated{

[superviewwillappear: animated];

self. label . text = Self . Backmessage ;

}

-(ibaction) GOTOBVC: ( ID ) Sender {

bviewcontroller *BVC = [[bviewcontrolleralloc] Initwithnibname:@ "Bviewcontroller"bundle:Nil ];

//AVC His references to BVC .

BVC. AVC = Self ;

[selfpresentviewcontroller: BVC animated:YES completion: nil];

}

STEP4:BVC before dismiss, assigns the value of the text box to the stored AVC

STEP5:AVC displays the value of the callback in the Viewwillappear

@interfacebviewcontroller ()

@property (weak,nonatomic) Iboutlet Uitextfield *textfield;

@end

@implementation Bviewcontroller

-(void) viewdidload

{

[superviewdidload];

}

-(ibaction) GOBACKAVC: ( ID ) Sender {

self. AVC . Backmessage = Self . TextField . text ;

[selfdismissviewcontrolleranimated: YES Completion:nil];

}

Solution Two: Delegate

/*

1. Defining the Agreement

1 ) protocol naming: class name +delegate

2) name of method: try to reflect the timing of sending messages

3 the parameters of the method: the first parameter must be the principal's own, and the subsequent parameters can be the secondary information sent to the agent by the principal party.

2. Define a property that stores a reference for the agent

3. send a message to the agent at the right time

*/

/*

in the process of returning values, Inputviewcontroller as the principal party, Aviewcontroller as an agent

1. compliance with agreements

2. Implementation Methods

3. Set yourself as an agent

*/

M beef C Original Blog--mvc value, reverse pass value