iphone - iOS 中的放大和缩小功能

Question

我在我的应用程序中编写了这段代码:

- (IBAction)ZoomInFunction{
@try{
    UITextField *test  = (UITextField *)[self.view viewWithTag:indexNews];
    NSLog(@"INDEX NEWS : %d", indexNews);

    UIFont *font = test.font;
    if(test.font == [font fontWithSize:22])
        test.font = [font fontWithSize:22];
    else
        test.font = [font fontWithSize:font.pointSize+2];
}@catch (NSException *err) {
    NSLog(@"Error handler : %@", err);
}

- (IBAction)ZoomOutFunction{
@try {
    UITextField *test  = (UITextField *)[self.view viewWithTag:indexNews];

    UIFont *font = test.font;
    if(test.font == [font fontWithSize:14])
        test.font = [font fontWithSize:14];
    else
        test.font = [font fontWithSize:font.pointSize-2];
}@catch (NSException *err) {
    NSLog(@"Error handler : %@", err);

有时代码运行良好，但有时会显示这样的错误。

Error handler : -[UIView font]: unrecognized selector sent to instance 0xac70780

Answer 1

仔细阅读这篇 Apple 文章，您将了解 IOS 中的放大和缩小功能。

下面是代码:

       UITextView *textView = [UITextView alloc] initWithFrame:CGRectMake(0, 0, 320, 200)];
    UIPinchGestureRecognizer *gestureRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(changeFontSize:)];
    [textView addGestureRecognizer:gestureRecognizer];

- (void)changeFontSize:(UIPinchGestureRecognizer *)gestureRecognizer 
 {
    UITextView *textView = (UITextView *)gestureRecognizer.view;
    float yourFontSize = gestureRecognizer.scale * FONT_SIZE;
    textView.font = [UIFont systemFontOfSize:yourFontSize];
 }

http://developer.apple.com/library/ios/#documentation/windowsviews/conceptual/UIScrollView_pg/ZoomZoom/ZoomZoom.html