我在我的应用程序中使用了这些代码来使我的textView垂直居中对齐，并且在iOS7.1之前一直有效。我想contentSize属性在iOS7.1中发生了变化你能帮我做什么？[textViewaddObserver:selfforKeyPath:@"contentSize"options:NSKeyValueObservingOptionNewcontext:nil];-(void)observeValueForKeyPath:(NSString*)keyPathofObject:(id)objectchange:(NSDictionary*)changecontext:(void*)

-(void)observeValueForKeyPath:(NSString*)keyPathofObject:(id)objectchange:(NSDictionary*)changecontext:(void*)context{NSLog(@"Hello");UITextView*tv=object;CGFloattopCorrect=([tvbounds].size.height-[tvcontentSize].height*[tvzoomScale])/2.0;topCorrect=(topCorrect我在Viewdidload中是这样调用的[myTextView1add