UITextView 字体垂直居中水平居中显示

 
 
import 
 
 
@interface TMVerticallyCenteredTextView : UITextView
 
 
@end
 

 
 
import "TMVerticallyCenteredTextView.h"
 
 
@interface TMVerticallyCenteredTextView()
 @end
 @implementation TMVerticallyCenteredTextView
 
 
 
  
(id)initWithFrame:(CGRect)frame
 {
 if (self = [super initWithFrame:frame])
 {
 self.textAlignment = NSTextAlignmentCenter;
 [self addObserver:self forKeyPath:@"contentSize" options: (NSKeyValueObservingOptionNew) context:NULL];
 }
 return self;
 }
 
 
 
 
 
  
(id)initWithCoder:(NSCoder *)aDecoder
 {
 if (self = [super initWithCoder:aDecoder])
 {
 self.textAlignment = NSTextAlignmentCenter;
 [self addObserver:self forKeyPath:@"contentSize" options: (NSKeyValueObservingOptionNew) context:NULL];
 }
 return self;
 }
 
 
 
 
-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
 {
 if ([keyPath isEqualToString:@"contentSize"])
 {
 UITextView *tv = object;
 CGFloat deadSpace = ([tv bounds].size.height - [tv contentSize].height);
 CGFloat inset = MAX(0, deadSpace/2.0);
 tv.contentInset = UIEdgeInsetsMake(inset, tv.contentInset.left, inset, tv.contentInset.right);
 }
 }
 
 
 
  
(void)dealloc
 {
 [self removeObserver:self forKeyPath:@"contentSize"];
 }