在登录界面中，UITextFiled左边添加图片
//设置左边添加的图片
UIImageView *userImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"login_user"]];
userImage.frame = CGRectMake(0, 0, CGRectGetHeight(self.userName.frame), CGRectGetHeight(self.userName.frame);
userImage.contentMode = UIViewContentViewModeCenter;
//图片添加到self.userName的左边
self.userName.leftView = userImage;
self.userName.leftViewMode = UITextFiledViewModeAlways;
动态监听UITextFiled的text变化
- 当动态监听UITextFiled的text变化时，可以使用本地通知事件或add Target来监听
- 通过本地通知
// 开始编辑
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(beginEditing) name:UITextFieldTextDidBeginEditingNotification object:self];
// 编辑中
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(editing) name:UITextFieldTextDidEndEditingNotification object:self];
// 结束编辑
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(endEditing) name:UITextFieldTextDidChangeNotification object:self];
- 通过addTarget:因UITextFiled继承UIControl，可以通过addTarget来监听文本框的变化
// 开始编辑
[self.textFiled addTarget:self action:@selector(beginEditing) forControlEvents:UIControlEventEditingDidBegin];
// 编辑中
[self.textFiled addTarget:self action:@selector(editing) forControlEvents:UIControlEventEditingChanged];
// 结束编辑
[self.textFiled addTarget:self action:@selector(endEditing) forControlEvents:UIControlEventEditingDidEnd];
// 'return key' ending editing
[self.textFiled addTarget:self action:@selector(endOnExit) forControlEvents:UIControlEventEditingDidEndOnExit];
友情资料：iOS_成才录
