從另一個方法目標中更新變量c

Question

因此，我是Objective C，XCode iOS的全新人物，所以我從一個簡單的計數器應用程序開始。

我已經設置了基本知識（增加按鈕按下分數），但我似乎無法獲得UILabel文本更新，每個按鈕按即每次我增加currentScore它不會更新currentScore變量內UILabel text

任何幫助將不勝感激！

#import "JPViewController.h" 

@implementation JPViewController 

int currentScore; 

- (void)viewDidLoad 
{ 

    [super viewDidLoad]; 

    //Init currentScore 
    currentScore = 0; 
    NSLog(@"Your score is %d", currentScore); 

    //Points text label 

    UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(100, 100, 290, 400)]; 
    label.text = [NSString stringWithFormat:@"Your score is: %d", currentScore]; 
    [label setFont:[UIFont boldSystemFontOfSize:16]]; 
    //TODO: Position points in centre. 
    [self.view addSubview:label]; 

    //Add Points Button 

    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem]; 
    [button setTitle:@"Press Me" forState:UIControlStateNormal]; 
    [button sizeToFit]; 
    button.center = CGPointMake(320/2, 60); 
    [button addTarget:self action:@selector(buttonPressed:) 
    forControlEvents:UIControlEventTouchUpInside]; 
    [self.view addSubview:button]; 

} 

- (void)buttonPressed:(UIButton *)button { 
    NSLog(@"Button Pressed"); 
    currentScore++; 
    NSLog(@"Your score is %d", currentScore); 
    //TODO: Update the label with the new currentScore here. 
} 

Answer 1

要用於側拉布勒你的按鈕做以下的事情

1）給出的標籤到標籤

UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(100, 100, 290, 400)]; 
    label.text = [NSString stringWithFormat:@"Your score is: %d", currentScore]; 
    [label setFont:[UIFont boldSystemFontOfSize:16]]; 
    //TODO: Position points in centre. 
    [label setTag:1000];//Give tag to your label 
    [self.view addSubview:label]; 

2）然後通過它的標籤按鈕方法獲取標籤

- (void)buttonPressed:(UIButton *)button { 
    NSLog(@"Button Pressed"); 
    currentScore++; 
    NSLog(@"Your score is %d", currentScore); 
    UILabel *label = (UILabel) [self.view viewWithTag:1000]; // you get your label reference here 
    [label setText:[NSString stringWithFormate:%d,currentScore]]; // then store your current score in your lable 
    //TODO: Update the label with the new currentScore here. 
} 

還是這第二種方法

1）讓您的UILabel可變全局像下面

@implementation JPViewController 
    { 
      UILabel *label; 
    } 

2）在viewDidLoad中（）

label = [[UILabel alloc]initWithFrame:CGRectMake(100, 100, 290, 400)]; 
     label.text = [NSString stringWithFormat:@"Your score is: %d", currentScore]; 
     [label setFont:[UIFont boldSystemFontOfSize:16]]; 
     //TODO: Position points in centre. 
     [self.view addSubview:label]; 

3）在您的按鈕事件

- (void)buttonPressed:(UIButton *)button { 
     NSLog(@"Button Pressed"); 
     currentScore++; 
     NSLog(@"Your score is %d", currentScore); 
     [label setText:[NSString stringWithFormate:%d,currentScore]]; // then store your current score in your lable 
     //TODO: Update the label with the new currentScore here. 
    } 

Answer 2

您應該創建一個@property（類變量）

@property int currentScore 

@implementation JPViewController 

- (void)viewDidLoad 
{ 

    [super viewDidLoad]; 

    //Init currentScore 
    self.currentScore = 0; 
    NSLog(@"Your score is %d", self.currentScore); 

    //Points text label 

    UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(100, 100, 290, 400)]; 
    label.text = [NSString stringWithFormat:@"Your score is: %d", self.currentScore]; 
    [label setFont:[UIFont boldSystemFontOfSize:16]]; 
    //TODO: Position points in centre. 
    [self.view addSubview:label]; 

    //Add Points Button 

    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem]; 
    [button setTitle:@"Press Me" forState:UIControlStateNormal]; 
    [button sizeToFit]; 
    button.center = CGPointMake(320/2, 60); 
    [button addTarget:self action:@selector(buttonPressed:) 
    forControlEvents:UIControlEventTouchUpInside]; 
    [self.view addSubview:button]; 

} 

- (void)buttonPressed:(UIButton *)button { 
    NSLog(@"Button Pressed"); 
    self.currentScore++; 
    NSLog(@"Your score is %d", self.currentScore); 
    //TODO: Update the label with the new currentScore here. 
}