SYPlaceHolderTextView:带有占位符的textview

SYPlaceHolderTextView 继承自UITextView，且带有占位符和block回调的自定义textview #import "SYPlaceHolderTextView.h" // 实例化 SYPlaceHolderTextView *textview = [[SYPlaceHolderTextView alloc] initWithFrame:CGRectMake(10.0, 10.0, (self.view.frame.size.width - 10.0 * 2), 80.0) view:self.view]; // 属性设置 textview.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.3]; textview.layer.cornerRadius = 5.0; textview.layer.masks