Textview Center文本对齐IOS 7

Ahs*_*san 3 iphone objective-c ios

-(void)observeValueForKeyPath:(NSString *)keyPath   ofObject:(id)object   change:(NSDictionary *)change   context:(void *)context 
{
    NSLog(@"Hello");
    UITextView *tv = object;
    CGFloat topCorrect = ([tv bounds].size.height - [tv contentSize].height * [tv zoomScale])  / 2.0;
    topCorrect = ( topCorrect < 0.0 ? 0.0 : topCorrect );
    tv.contentOffset = (CGPoint){.x = 0, .y = -topCorrect};
}
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我在Viewdidload中这样称呼它

[myTextView1 addObserver:self forKeyPath:@"contentSize" options:(NSKeyValueObservingOptionNew) context:NULL];
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use*_*099 12

textView.textAlignment = NSTextAlignmentCenter;
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